5
5.0

Jun 30, 2018
06/18

by
Felipe Torres; Dora Altbir; Miguel Kiwi

texts

#
eye 5

#
favorite 0

#
comment 0

The inclusion of a Dzyaloshinskii-Moriya short range antisymmetric interaction induces spontaneous magnetization, at nonzero temperatures, in one and two dimensions. It is shown that quantum fluctuations are reduced by the Dzyaloshinskii-Moriya interaction, but short range correlations are increased, thereby allowing to obtain long range magnetic order in these low dimensional systems.

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1403.6505

6
6.0

Jun 30, 2018
06/18

by
W. Schoepe; R. Hänninen; M. Niemetz

texts

#
eye 6

#
favorite 0

#
comment 0

The onset of turbulent flow around an oscillating sphere in superfluid $^4$He is known to occur at a critical velocity $v_c \sim \sqrt{\kappa\omega}$ where $\kappa$ is the circulation quantum and $\omega$ is the oscillation frequency. But it is also well known that initially in a first up-sweep of the oscillation amplitude, $v_c$ can be considerably exceeded before the transition occurs, thus leading to a strong hysteresis in the velocity sweeps. The velocity amplitude $v_c^* > v_c$ where...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1412.5377

13
13

Jun 27, 2018
06/18

by
B. G. Márkus; F. Márkus

texts

#
eye 13

#
favorite 0

#
comment 0

The motivation of this work is to get an additional insight into the irreversible energy dissipation on the quantum level. The presented examination procedure is based on the Feynman path integral method that is applied and widened towards the calculation of the kernel of a quantum mechanical damped oscillator. Here, it is shown that the energy loss of the oscillator can be generated by the introduced harmonic complex potential. The related damped wave function, however, does not pertain to the...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1505.06874

13
13

Jun 27, 2018
06/18

by
Yousef Yousefi

texts

#
eye 13

#
favorite 0

#
comment 0

We discuss system with non-isotropic non-Heisenberg Hamiltonian with nearest neighbor exchange within a mean field approximation process. We drive equations describing non-Heisenberg non-isotropic model using coherent states in real parameters and then obtain dispersion equations of spin wave of dipole and quadrupole branches for a small linear excitation from the ground state. In final, soliton solution for quadrupole branches for these linear equations obtained.

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1505.03244

7
7.0

Jun 29, 2018
06/18

by
Dmytro Khomenko; Pankaj Mishra; Anna Pomyalov

texts

#
eye 7

#
favorite 0

#
comment 0

We study the coupled dynamics of normal and superfluid components of the superfluid $^4$He in the channel considering the counterflow turbulence with laminar normal component. In particular, we calculated profiles of the normal velocity, the mutual friction, the vortex line density and other flow properties and compared them to the case when the dynamic of the normal component is "frozen". We have found that the coupling between the normal and superfluid components leads to flattening...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1608.06162

7
7.0

Jun 30, 2018
06/18

by
Michael Niemetz; Risto Hänninen; Wilfried Schoepe

texts

#
eye 7

#
favorite 0

#
comment 0

The flow of superfluid $^4$He around a translationally oscillating sphere, levitating without mechanical support, can either be laminar or turbulent, depending on the velocity amplitude. Below a critical velocity $v_c$ that scales as $\omega ^{1/2}$, and is temperature independent below 1 K, the flow is laminar (potential flow). Below 0.5 K the linear drag force is caused by ballistic phonon scattering that vanishes as T$^4$ until background damping, measured in the empty cell, becomes dominant...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1701.05733

6
6.0

Jun 29, 2018
06/18

by
G. E. Volovik

texts

#
eye 6

#
favorite 0

#
comment 0

There are many topological faces of the superfluid phases of $^3$He. These superfluids contain various topological defects and textures. The momentum space topology of these superfluids is also nontrivial, as well as the topology in the combined (${\bf p},{\bf r})$ phase space, giving rise to topologically protected Dirac, Weyl and Majorana fermions living in bulk, on the surface and within the topological objects.

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1602.02595

3
3.0

Jun 29, 2018
06/18

by
Shinichi Ikawa; Makoto Tsubota

texts

#
eye 3

#
favorite 0

#
comment 0

We perform a numerical simulation of the dynamics of quantized vortices produced by coflow in a square channel using the vortex filament model. Unlike the situation in thermal counterflow, where the superfluid velocity $v_{\rm s}$ and normal-fluid velocity $v_{\rm n}$ flow in opposite directions, in coflow, $v_{\rm s}$ and $v_{\rm n}$ flow in the same direction. Quantum turbulence in thermal counterflow has been long studied theoretically and experimentally, and its various features have been...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1602.08252

5
5.0

Jun 29, 2018
06/18

by
S. N. Klimin; J. Tempere; J. T. Devreese

texts

#
eye 5

#
favorite 0

#
comment 0

In the present work, the problem of an all-coupling analytic description for the optical conductivity of the Froehlich polaron is treated, with the goal being to bridge the gap in validity range that exists between two complementary methods: on the one hand the memory function formalism and on the other hand the strong-coupling expansion based on the Franck-Condon picture for the polaron response. At intermediate coupling, both methods were found to fail as they do not reproduce Diagrammatic...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1606.00605

6
6.0

Jun 29, 2018
06/18

by
M. Motta; G. Bertaina; E. Vitali; D. E. Galli; M. Rossi

texts

#
eye 6

#
favorite 0

#
comment 0

We study the response of one-dimensional liquid $^4$He to weak perturbations relying on the dynamical structure factor, $S(q,\omega)$, recently obtained via ab-initio techniques [Phys. Rev. Lett. 116, 135302 (2016)]. We evaluate the drag force, $F_v$, experienced by an impurity moving along the system with velocity $v$ and the static response function, $\chi(q)$, describing the density modulations induced by a periodic perturbation with wave vector $q$.

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1607.05301

3
3.0

Jun 30, 2018
06/18

by
Timothy R. Prisk; Matthew S. Bryan; Paul. E. Sokol; Garrett E. Granroth; Saverio Moroni; Massimo Boninsegni

texts

#
eye 3

#
favorite 0

#
comment 0

We report high-resolution neutron Compton scattering measurements of liquid $^4$He under saturated vapor pressure. There is excellent agreement between the observed scattering and ab initio predictions of its lineshape. Quantum Monte Carlo calculations predict that the Bose condensate fraction is zero in the normal fluid, builds up rapidly just below the superfluid transition temperature, and reaches a value of approximately $7.5\%$ below 1 K. We also used model fit functions to obtain from the...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1703.03018

7
7.0

Jun 29, 2018
06/18

by
Daniel Wiśniewski; Alexander Karabanov; Igor Lesanovsky; Walter Köckenberger

texts

#
eye 7

#
favorite 0

#
comment 0

We discuss the polarization dynamics during solid effect dynamic nuclear polarization (DNP) in a central spin model that consists of an electron surrounded by many nuclei. To this end we use a recently developed formalism and validate first its performance by comparing its predictions to results obtained by solving the Liouville von Neumann master equation. The use of a Monte Carlo method in our formalism makes it possible to significantly increase the number of spins considered in the model...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1601.04921

3
3.0

Jun 30, 2018
06/18

by
Alexander T. Holmes

texts

#
eye 3

#
favorite 0

#
comment 0

A new method is presented for the analysis of small angle neutron scattering data from quasi-2D systems such as flux lattices, Skyrmion lattices, and aligned liquid crystals. A significant increase in signal to noise ratio, and a natural application of the Lorentz factor can be achieved by taking advantage of the knowledge that all relevant scattering is centered on a plane in reciprocal space. The Bayesian form ensures that missing information is treated in a controlled way and can be...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1404.0833

5
5.0

Jun 30, 2018
06/18

by
P. J. Heikkinen; S. Autti; V. B. Eltsov; R. P. Haley; V. V. Zavjalov

texts

#
eye 5

#
favorite 0

#
comment 0

Coherent precession of trapped Bose-Einstein condensates of magnons is a sensitive probe for magnetic relaxation processes in superfluid 3He-B down to the lowest achievable temperatures. We use the dependence of the relaxation rate on the density of thermal quasiparticles to implement thermometry in 3He-B at temperatures below 300 $\mu$K. Unlike popular vibrating wire or quartz tuning fork based thermometers, magnon condensates allow for contactless temperature measurement and make possible an...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1401.2953

3
3.0

Jun 30, 2018
06/18

by
Mikhail Silaev; G. E. Volovik

texts

#
eye 3

#
favorite 0

#
comment 0

We consider Andreev-Majorana (AM) bound states with zero energy on surfaces, interfaces and vortices in different phases of the $p$-wave superfluids. We discuss the chiral superfluid $^3$He-A, and time reversal invariant phases: superfluid $^3$He-B, planar and polar phases. The AM zero modes are determined by topology in bulk, and they disappear at the quantum phase transition from the topological to non-topological state of the superfluid. The topology demonstrates the interplay of dimensions....

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1405.1007

6
6.0

Jun 30, 2018
06/18

by
Eric Varoquaux

texts

#
eye 6

#
favorite 0

#
comment 0

Nearly five decades have elapsed since the seminal 1966 paper of P.W. Anderson on the flow of superfluid helium, $^4$He at that time. Some of his "Considerations" -- the role of the quantum phase as a dynamical variable, the interplay between the motion of quantised vortices and potential superflow, its incidence on dissipation in the superfluid and the appearance of critical velocities, the quest for the hydrodynamic analogues of the Josephson effects in helium -- and the way they...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1406.5629

3
3.0

Jun 30, 2018
06/18

by
F. Claro; R. Fuchs; P. Robles; R. Rojas

texts

#
eye 3

#
favorite 0

#
comment 0

We discuss the force and torque acting on spherical particles in an ensemble in the presence of a uniform AC electric field. We show that for a torque causing particle rotation to appear the particle must be absorptive. Our proof includes all electromagnetic excitations, which in the case of two or more particles gives rise to one or more resonances in the spectrum of force and torque depending on interparticle distance. Several peaks are found in the force and torque between two spheres at...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1408.5408

3
3.0

Jun 30, 2018
06/18

by
Igor V. Blinov

texts

#
eye 3

#
favorite 0

#
comment 0

A new method for finding electronic structure and wavefunctions of electrons in quasiperiodic potential is introduced. To obtain results it uses slightly modified Schrodinger equation in spaces of dimensionality higher than physical space. It enables to get exact results for quasicrystals without expensive non-exact calculations. New method tested on one-dimensional quasiperiodic screened Coulomb potential.

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1409.8084

3
3.0

Jun 29, 2018
06/18

by
Leonid Prigozhin; Vladimir Sokolovsky; John W. Barrett; Sergey E. Zirka

texts

#
eye 3

#
favorite 0

#
comment 0

We consider the quasi-static magnetic hysteresis model based on a dry-friction like representation of magnetization. The model has a consistent energy interpretation, is intrinsically vectorial, and ensures a direct calculation of the stored and dissipated energies at any moment in time, and hence not only on the completion of a closed hysteresis loop. We discuss the variational formulation of this model and derive an efficient numerical scheme, avoiding the usually employed approximation which...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1605.08748

3
3.0

Jun 29, 2018
06/18

by
Jean-Sebastien Gagnon; David Hochberg; Juan Perez-Mercader

texts

#
eye 3

#
favorite 0

#
comment 0

We characterize the influence that external noise, with both spatial and temporal correlations, has on the scale dependence of the reaction parameters of a cubic autocatalytic reaction diffusion (CARD) system. Interpreting the CARD model as a primitive reaction scheme for a living system, the results indicate that power-law correlations in environmental fluctuations can either decrease or increase the rates of nutrient decay and the rate of autocatalysis (replication) on small spatial and...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1612.02318

11
11

Jun 28, 2018
06/18

by
E. Perfetto; D. Sangalli; A. Marini; G. Stefanucci

texts

#
eye 11

#
favorite 0

#
comment 0

In this work we propose an accurate first-principle approach to calculate the transient photo--absorption spectrum measured in Pump\&\,Probe experiments. We formulate a condition of {\em adiabaticity} and thoroughly analyze the simplifications brought about by the fulfillment of this condition in the non--equilibrium Green's function (NEGF) framework. Starting from the Kadanoff-Baym equations we derive a non--equilibrium Bethe--Salpeter equation (BSE) for the response function that can be...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1507.01786

12
12

Jun 28, 2018
06/18

by
Anatoly Kuklov

texts

#
eye 12

#
favorite 0

#
comment 0

A significant accumulation of matter in solid Helium-4 observed during the superflow events, dubbed as the giant isochoric compressibility (or the syringe effect), is discussed within the model of dislocations with superfluid core. It is shown that solid Helium-4 in a contact with superfluid reservoir can develop a bistability with respect to the syringe fraction, with the threshold for the bias by chemical potential determined by a typical free length of dislocations with superfluid core. The...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1507.06966

11
11

Jun 28, 2018
06/18

by
Simone Babuin; Emil Varga; William F. Vinen; Ladislav Skrbek

texts

#
eye 11

#
favorite 0

#
comment 0

We report on studies of quantum turbulence with second-sound in superfluid 4He in which the turbulence is generated by the flow of the superfluid component through a wide square channel, the ends of which are plugged with sintered silver superleaks, the flow being generated by compression of a bellows. The superleaks ensure that there is no net flow of the normal fluid. In an earlier paper (Phys. Rev. B, 86, 134515 (2012)) we have shown that steady flow of this kind generates a density of...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1509.01374

6
6.0

Jun 29, 2018
06/18

by
Victor Lakhno

texts

#
eye 6

#
favorite 0

#
comment 0

Large-radius translation invariant (TI) bipolarons are considered in a one-dimensional Holstein molecular chain. Criteria of their stability are obtained. The energy of a translation invariant bipolaron is shown to be lower than that of a bipolaron with broken symmetry. The results obtained are applied to the problem of superconductivity in 1D-systems. It is shown that TI-bipolaron mechanism of Bose-Einstein condensation can support superconductivity even for infinite chain.

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1606.02219

17
17

Jun 28, 2018
06/18

by
Walter Tarantino

texts

#
eye 17

#
favorite 0

#
comment 0

Predictivity of the Kohn-Sham approach to dynamical problems, when regarded as an initial value problem in a time-dependent density functional framework, is analysed for a class of models for which the argument devised in the work of Maitra et al. (Phys. Rev. A 78, 056501 (2008), arXiv:cond-mat/0710.0018) for the standard electronic many-body problem does not apply. The original argument is here extended and revised. As a result, predictivity for this class of problems seems possible only at...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1506.04602

13
13

Jun 28, 2018
06/18

by
Ashkan Haji Hosseinloo; Konstantin Turitsyn

texts

#
eye 13

#
favorite 0

#
comment 0

Narrow bandwidth and easy detuning, inefficiency in broadband and non-stationary excitations, and difficulties in matching linear harvester's resonance frequency to low-frequency excitations at small scales, have convinced the researchers to investigate the nonlinear, in particular the bistable energy harvesters in the recent years. However, the bistable harvesters suffer from co-existing low and high energy orbits, and sensitivity to initial conditions, and have been recently proven...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1508.02126

6
6.0

Jun 30, 2018
06/18

by
Davide E. Galli; Luciano Reatto; Maurizio Rossi

texts

#
eye 6

#
favorite 0

#
comment 0

We have performed a microscopic study of a straight quantized vortex line in three dimensions in condensed $^4$He at zero temperature using the Shadow Path Integral Ground State method and the fixed-phase approximation. We have characterized the energy and the local density profile around the vortex axis in superfluid $^4$He at several densities, ranging from below the equilibrium density up to the overpressurized regime. For the Onsager-Feynman (OF) phase our results are exact and represent a...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1405.7589

4
4.0

Jun 28, 2018
06/18

by
S. T. Chui; Shubo Wang; C. T. Chan

texts

#
eye 4

#
favorite 0

#
comment 0

We discuss a way to exploit the conformal mapping to study the response of a finite metallic element of arbitrary shape to an external electromagnetic field at finite frequencies. This provides a simple way to study different physics issues and provides new insights that include the issue of vorticity and eddy current, and the nature of the divergent electric field at the boundaries and at corners. The nature of the resonance can be directly addressed and clarified. We study an example of an...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1511.07405

6
6.0

Jun 29, 2018
06/18

by
G. E. Volovik

texts

#
eye 6

#
favorite 0

#
comment 0

Different types of Lifshitz transitions are governed by topology in momentum space. They involve the topological transitions with the change of topology of Fermi surfaces, Weyl and Dirac points, nodal ines, and also the transitions between the fully gapped states.

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1606.08318

4
4.0

Jun 29, 2018
06/18

by
T. S. Riekki; M. S. Manninen; J. T. Tuoriniemi

texts

#
eye 4

#
favorite 0

#
comment 0

Bulk superfluid helium supports two sound modes: first sound is an ordinary pressure wave, while second sound is a temperature wave, unique to inviscid superfluid systems. These sound modes do not usually exist independently, but rather variations in pressure are accompanied by variations in temperature, and vice versa. We studied the coupling between first and second sound in dilute $^3$He - superfluid $^4$He mixtures, between 1.6 K and 2.2 K, at $^3$He concentrations ranging from 0 to 11 %,...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1607.08767

13
13

Jun 26, 2018
06/18

by
E. Zemma; M. Tsubota; J. Luzuriaga

texts

#
eye 13

#
favorite 0

#
comment 0

Visualization using tracer particles is a relatively new tool available for the study of superfluid turbulence and flow, which is applied here to oscillating objects submerged in the liquid. We report observations of a structure seen in videos taken from outside a cryostat filled with superfluid helium at 2 K, which is possibly a vortex loop attached to an oscillator. The feature, which has the shape of an incomplete arch, is visualized due to the presence of solid H2 tracer particles and is...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1501.06776

4
4.0

Jun 30, 2018
06/18

by
V. P. Mineev

texts

#
eye 4

#
favorite 0

#
comment 0

The magnetic dipole-dipole interaction does not prevent existence of half-quantum vortices in the polar phase of superfluid He-3 which can be stable in uniaxial anisotropic aerogel. Here we discus this exotic possibility. After developing a phenomenological theory of phase transition from the normal to polar superfluid state and then to axipolar superfluid state we calculate the NMR properties of such type superfluids at the rest or under rotation filled by an array either single quantum or...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1402.2111

4
4.0

Jun 30, 2018
06/18

by
Todd Karin; Scott Dunham; Kai-Mei Fu

texts

#
eye 4

#
favorite 0

#
comment 0

The nitrogen vacancy (NV) center in diamond is a sensitive probe of magnetic field and a promising qubit candidate for quantum information processing. The performance of many NV-based devices improves by aligning the NV(s) parallel to a single crystallographic direction. Using ab initio theoretical techniques, we show that NV orientation can be controlled by high-temperature annealing in the presence of strain under currently accessible experimental conditions. We find that $(89\pm7)\%$ of NVs...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1406.0041

5
5.0

Jun 30, 2018
06/18

by
Duk Y. Kim; Moses H. W. Chan

texts

#
eye 5

#
favorite 0

#
comment 0

The resonant period drop observed at low temperatures in torsional oscillators containing solid helium had been interpreted as a signature of supersolid. However, it was found that the shear modulus increase found in solid helium at the same low temperature could also decrease the resonant period of the torsional oscillator. We report the results of a study in two different torsional oscillators that were specially designed to minimize the shear modulus effect and maximize any possible...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1407.2132

4
4.0

Jun 30, 2018
06/18

by
G. Stefanucci; Y. Pavlyukh; A. -M. Uimonen; R. van Leeuwen

texts

#
eye 4

#
favorite 0

#
comment 0

We present a diagrammatic approach to construct self-energy approximations within many-body perturbation theory with positive spectral properties. The method cures the problem of negative spectral functions which arises from a straightforward inclusion of vertex diagrams beyond the GW approximation. Our approach consists of a two-steps procedure: we first express the approximate many-body self-energy as a product of half-diagrams and then identify the minimal number of half-diagrams to add in...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1408.6163

3
3.0

Jun 30, 2018
06/18

by
Ashkan Haji Hosseinloo; Konstantin Turitsyn

texts

#
eye 3

#
favorite 0

#
comment 0

Ease of miniaturization, and less or no maintenance, among other advantages, have pushed towards replacement of conventional batteries with energy harvesters in particular, vibratory energy harvesters. In the recent years, nonlinearity has been intentionally introduced into the otherwise linear energy harvesters in the hope of increasing the frequency bandwidth and power density. However, fundamental limits on the harvestable energy of a harvester subjected to an arbitrary excitation force is...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1410.1429

4
4.0

Jun 30, 2018
06/18

by
A. P. Itin; M. I. Katsnelson

texts

#
eye 4

#
favorite 0

#
comment 0

We consider 1D lattices described by Hubbard or Bose-Hubbard models, in the presence of periodic high-frequency perturbations, such as uniform ac force or modulation of hopping coefficients. Effective Hamiltonians for interacting particles are derived using an averaging method resembling classical canonical perturbation theory. As is known, a high-frequency force may renormalize hopping coefficients, causing interesting phenomena such as coherent destruction of tunnelling and creation of...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1401.0402

8
8.0

Jun 29, 2018
06/18

by
Jérémy Bon; Serge Galliou; Roger Bourquin

texts

#
eye 8

#
favorite 0

#
comment 0

This paper brings out results of a measurement campaign aiming to determine the temperature coefficients of synthetic quartz elastic constants at liquid helium temperature. The method is based on the relationship between the resonance frequencies of a quartz acoustic cavity and the elastic constants of the material. The temperature coefficients of the elastic constants are extracted from experimental frequency-temperature data collected from a set of resonators of various cut angles, because of...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1607.04584

9
9.0

Jun 29, 2018
06/18

by
Mojtaba Forghani; Nicolas G. Hadjiconstantinou

texts

#
eye 9

#
favorite 0

#
comment 0

We present a method for reconstructing the phonon relaxation time distribution $\tau_{\omega}= \tau (\omega)$ (including polarization) in a material from thermal spectroscopy data. The distinguishing feature of this approach is that it does not make use of the effective thermal conductivity concept and associated approximations. The reconstruction is posed as an optimization problem in which the relaxation times $\tau_{\omega}= \tau (\omega)$ are determined by minimizing the discrepancy between...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1609.05864

5
5.0

Jun 28, 2018
06/18

by
Dmytro Khomenko; Victor S. L'vov; Anna Pomyalov; Itamar Procaccia

texts

#
eye 5

#
favorite 0

#
comment 0

In mechanically driven superfluid turbulence the mean velocities of the normal- and superfluid components are known to coincide: $\mathbf U_{\text{n}} =\mathbf U_{\text{s}}$. Numerous laboratory, numerical and analytical studies showed that under these conditions the mutual friction between the normal- and superfluid velocity components couples also their fluctuations: $\mathbf u'_{\text{n}}(\mathbf r,t) \approx \mathbf u'_{\text{s}}(\mathbf r,t)$ almost at all scales. In this paper we show...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1509.03566

5
5.0

Jun 30, 2018
06/18

by
Ye. Vekhov; R. B. Hallock

texts

#
eye 5

#
favorite 0

#
comment 0

The thermo-mechanical effect in superfluid helium is used to create an initial chemical potential difference, $\Delta \mu_0$, across a solid $^4$He sample. This $\Delta \mu_0$ causes a flow of helium atoms from one reservoir filled with superfluid helium, through a sample cell filled with solid helium, to another superfluid-filled reservoir until chemical potential equilibrium is restored. The solid helium sample is separated from each of the reservoirs by Vycor rods that allow only the...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1407.4427

6
6.0

Jun 29, 2018
06/18

by
N. Lo Gullo; L. Vittadello; M. Bazzan; L. Dell'Anna

texts

#
eye 6

#
favorite 0

#
comment 0

We investigate, theoretically and experimentally,the properties of diffraction spectra of Fibonacci lattices with arbitrary spacings. We show that, by means of a suitable composition rule, a Fibonacci sequence can be mapped into another one with a different lattice spacing. In this way we are able to define equivalence classes of Fibonacci structures and their generators, namely the Fibonacci sequences from which all the others can be obtained by compostion rule. We show that each class can be...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1601.07499

6
6.0

Jun 28, 2018
06/18

by
David Z. Li; R. H. Anderson; M. D. Miller

texts

#
eye 6

#
favorite 0

#
comment 0

We calculate expressions for the state-dependent quasiparticle lifetime, the thermal conductivity $\kappa$, the shear viscosity $\eta$, and discuss the spin diffusion coefficient $D$ for Fermi-liquid films in two dimensions. The expressions are valid for low temperatures and arbitrary polarization. The low-temperature expressions for the transport coefficients are essentially exact. We find that $\kappa^{-1} \sim T \ln{T}$, and $\eta^{-1} \sim T^{2}$ for arbitrary polarizations $0 \le...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1507.02596

3
3.0

Jun 30, 2018
06/18

by
G. De Filippis; V. Cataudella; A. de Candia; A. S. Mishchenko; N. Nagaosa

texts

#
eye 3

#
favorite 0

#
comment 0

The Kubo formula for the electrical conductivity is rewritten in terms of a sum of Drude-like contributions associated to the exact eigenstates of the interacting system, each characterized by its own frequency-dependent relaxation time. The structure of the novel and equivalent formulation, weighting the contribution from each eigenstate by its Boltzmann occupation factor, simplifies considerably the access to the static properties (dc conductivity) and resolves the long standing difficulties...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1406.2917

3
3.0

Jun 28, 2018
06/18

by
Fengpei Sun; Jie Zou; Zakhar A. Maizelis; Ho Bun Chan

texts

#
eye 3

#
favorite 0

#
comment 0

We demonstrate experimentally the possibility of revealing fluctuations in the eigenfrequency of a resonator when the frequency noise is of the telegraph type. Using a resonantly driven micromechanical resonator, we show that the time-averaged vibration amplitude spectrum exhibits two peaks. They merge with an increasing rate of frequency switching and the spectrum displays an analog of motional narrowing. We also show that the moments of the complex amplitude depend strongly on the frequency...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1511.00893

3
3.0

Jun 28, 2018
06/18

by
Giorgio Krstulovic

texts

#
eye 3

#
favorite 0

#
comment 0

Low-temperature grid generated turbulence is investigated by using numerical simulations of the Gross-Pitaevskii equation. The statistics of regularized velocity increments are studied. Increments of the incompressible velocity are found to be skewed for turbulent states. Results are later confronted with the (quasi) homogeneous and isotropic Taylor-Green flow, revealing the universality of the statistics. For this flow, the statistics are found to be intermittent and a Kolmogorov constant...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1512.03382

3
3.0

Jun 28, 2018
06/18

by
M. Apostol; L. C. Cune

texts

#
eye 3

#
favorite 0

#
comment 0

Molecular rotation spectra, generated by the coupling of the molecular electric-dipole moments to an external time-dependent electric field, are discussed in a few particular conditions which can be of some experimental interest. First, the spherical-pendulum molecular model is reviewed, with the aim of introducing an approximate method which consists in the separation of the azimuthal and zenithal motions. Second, rotation spectra are considered in the presence of a static electric field. Two...

Topics: Other Condensed Matter, Condensed Matter

Source: http://arxiv.org/abs/1512.04231

3
3.0

Jun 29, 2018
06/18

by
R. Wieser

texts

#
eye 3

#
favorite 0

#
comment 0

The dynamics of a single magnetic Skyrmion in an atomic spin system under the influence of Scanning Tunneling Microscope is investigated by computer simulations solving the Landau-Lifshitz-Gilbert equation. Two possible scenarios are described: manipulation with aid of a spin-polarized tunneling current and by an electric field created by the scanning tunneling microscope. The dynamics during the creation and annihilation process is studied and the possibility to move single Skyrmions is showed.

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1609.06797

4
4.0

Jun 29, 2018
06/18

by
Luca Galantucci; Michele Sciacca; Carlo F. Barenghi

texts

#
eye 4

#
favorite 0

#
comment 0

We perform fully-coupled numerical simulations of helium II pure superflows in a channel, with vortex- line density typical of experiments. Peculiar to our model is the computation of the back-reaction of the superfluid vortex motion on the normal fluid and the presence of solid boundaries. We recover the uniform vortex-line density experimentally measured employing second sound resonators and we show that pure superflow in helium II is associated with a large-scale circulation of the normal...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1610.03690

3
3.0

Jun 29, 2018
06/18

by
Pavel Kliuiev; Tatiana Latychevskaia; Juerg Osterwalder; Matthias Hengsberger; Luca Castiglioni

texts

#
eye 3

#
favorite 0

#
comment 0

Electronic wave functions of planar molecules can be reconstructed via inverse Fourier transform of angle-resolved photoelectron spectroscopy (ARPES) data, provided the phase of the electron wave in the detector plane is known. Since the recorded intensity is proportional to the absolute square of the Fourier transform of the initial state wave function, information about the phase distribution is lost in the measurement. It was shown that the phase can be retrieved in some cases by iterative...

Topics: Condensed Matter, Other Condensed Matter

Source: http://arxiv.org/abs/1609.01469