We find that if solid xenon is formed from liquid xenon, denoted "ice", there is a 10% increase of $^{129}$Xe longitudinal relaxation $T_1$ time (taken at 77 K and 2 Tesla) over a trickle-freeze formation, denoted "snow". Forming xenon ice also gives unprecedented reproducibility of $^{129}$Xe $T_1$ measurements across a range of 77-150 K. This temperature dependence roughly follows the theory of spin-rotation mediated by Raman scattering of harmonic phonons (SRRS), though it results in a smaller-than-predicted spin-rotation coupling strength $c_{K0}/h$. Enriched ice $^{129}$Xe $T_1$ experiments show no isotopic dependence in bulk relaxation mechanisms at 77 K and at kilogauss fields.
We investigate adsorption of a gas on the flat surface of a solid deformable adsorbent taking into account thermal fluctuations and analyze in detail the effect of thermal fluctuations on the adsorbent deformation in adsorption. The condition for coexistence of two states of a bistable system of adsorbed particles is derived. We establish the specific properties of the adsorption-induced surface normal relaxation of an adsorbent caused by thermal fluctuations. The mean transition times between two stable states of the bistable system are derived in the parabolic approximation and in the genera…
Present paper reports, the structural, microstructural, electrical, dielectric properties and ion dynamics of a sodium based solid polymer electrolyte films comprising of PEO8-NaPF6+ x wt. % SN. The structural and surface morphology properties have been investigated by XRD and FESEM. Different microscopic interaction among the polymer, salt and SN have been analyzed through FTIR. The dielectric permittivity and loss tangent enable us to estimate the dc conductivity, dielectric strength, double layer capacitance, and relaxation time. The loss tangent relaxation peak shifts towards high-frequenc…
Ultrafast electron dynamics of solids after an absorption of femtosecond laser pulse is governed by electron-electron, electron-phonon, phonon-electron, and phonon-phonon collisions. It is of importance to construct a framework for interpreting experimental observations correctly. In this paper we review recent developments of modeling the relaxation dynamics of solids. We discuss the ultrafast relaxation in respect to the effective temperature dynamics and the excess energy dynamics.
Ferromagnets are believed to exhibit strongly anisotropic spin relaxation, with relaxation lengths for spin longitudinal to magnetization significantly longer than those for spin transverse to magnetization. Here we characterize the anisotropy of spin relaxation in Co using the spin pumping contribution to Gilbert damping in noncollinearly magnetized Py$_{1-x}$Cu$_{x}$/Cu/Co trilayer structures. The static magnetization angle between Py$_{1-x}$Cu$_{x}$ and Co, adjusted under field bias perpendicular to film planes, controls the projections of longitudinal and transverse spin current pumped fro…
Spin-phonon coupling is the main drive of spin relaxation and decoherence in solid-state semiconductors at finite temperature. Controlling this interaction is a central problem for many disciplines, ranging from magnetic resonance to quantum technologies. Spin relaxation theories have been developed for almost a century but often employ a phenomenological description of phonons and their coupling to spin, resulting in a non-predictive tool and hindering our detailed understanding of spin dynamics. Here we combine fourth-order time-local quantum master equations with advanced electronic structu…
We show that the defect data parameters related to various defect processes, e.g., formation, migration, dielectric relaxation parameters, obey a universal law. In particular, the defect entropies scale with the defect enthalpies irrespective of the process considered. A concrete example is given here for SrF$_2$ by considering the dielectric relaxation parameters (R$_1$ relaxation mechanism) for crystals doped with trivalent ions of Ce, Eu and Gd, parameters for the anion Frenkel formation as well as for the migration of anion vacancy and the anion interstitial motion.
We present systematic measurements of longitudinal relaxation rates ($1/T_1$) of spin polarization in the ground state of the nitrogen-vacancy (NV$^-$) color center in synthetic diamond as a function of NV$^-$ concentration and magnetic field $B$. NV$^-$ centers were created by irradiating a Type 1b single-crystal diamond along the [100] axis with 200 keV electrons from a transmission electron microscope with varying doses to achieve spots of different NV$^-$ center concentrations. Values of ($1/T_1$) were measured for each spot as a function of $B$.
For certain non-magnetic solids with low symmetry the occurrence of spin-polarized longitudinal currents is predicted. These arise due to an interplay of spin-orbit interaction and the particular crystal symmetry. This result is derived using a group-theoretical scheme that allows investigating the symmetry properties of any linear response tensor relevant to the field of spintronics. For the spin conductivity tensor it is shown that only the magnetic Laue group has to be considered in this context. Within the introduced general scheme also the spin Hall- and additional related transverse effe…
Using very long molecular dynamics simulation runs, temperature protocols spanning up to five orders of magnitude in time-scales are performed to investigate thermally activated structural relaxation in a model amorphous solid. The simulations demonstrate significant local structural excitations as a function of increasing temperature and show that enthalpy rather than energy is primarily responsible for relaxation. The observed enthalpy changes are of the order seen in experiment, and can be correlated with the level of internal hydrostatic stress homogenization and icosahedral content within…
Ultrafast light-matter interaction is a powerful tool for the study of solids. Upon laser excitation, carrier multiplication and lattice acceleration beyond thermal velocity can occur, as a result of far-from-equilibrium carrier relaxation. The roles of electron-electron and electron-phonon scatterings are identified by first-principles dynamic simulations, from which a unified phase diagram emerges. It not only explains the experimentally-observed "inertial" melting but also predicts abnormal damping by Pauli Exclusion Principle with a new perspective on ultrahigh-intensity laser applications…
Energetic disorder in disordered organic solids has been found to alter their physical parameters. Here, we have demonstrated, by means of Monte-Carlo simulation and experiments, that the electroluminescence (EL) spectrum is dependent on energetic disorder. This dependence has been attributed to the charge carrier relaxation during hopping process. The dependence of EL spectrum on energetic disorder makes it temperature dependent and temperature dependence has been found to vary with energetic disorder in a variety of materials. The simulation has been performed by taking the relaxation of cha…
We propose a new material viscoelastic model and mathematical solution to simulate relaxation modulus and viscoelastic response. The model formula of relaxation modulus is extended from sigmoidal function considering nonlinear strain hardening and softening. Its physical mechanism can be interpreted by a spring network viscous medium model with only five parameters in a simpler format than the molecular-chain based polymer models to represent general materials. We also developed a three-dimensional finite-element method and robust numerical algorithms to implement this model for solving partia…
The spin relaxation time in solids is determined by several competing energy scales and processes and distinct methods are called for to analyze the various regimes. We present a stochastic model for the spin dynamics in solids which is equivalent to solving the spin Boltzmann equation and takes the relevant processes into account on equal footing. The calculations reveal yet unknown parts of the spin-relaxation phase diagram, where strong spin-dephasing occurs in addition to spin-relaxation. Spin-relaxation times are obtained for this regime by introducing the numerical Loschmidt echo. This a…
The realization of green and economically friendly energy storage systems needs materials with outstanding properties. Future batteries based on Na as an abundant element take advantage of non-flammable ceramic electrolytes with very high conductivities. $\rm Na{_{3}}Zr{_{2}}(SiO{_{4}}){_{2}}PO{_{4}}$-type superionic conductors are expected to pave the way for inherently safe and sustainable all-solid-state batteries. So far, only little information has been extracted from spectroscopic measurements to clarify the origins of fast ionic hopping on the atomic length scale. Here we combined broad…
A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations. Here, we report that the crystalline solid AgCrSe2 has liquid-like thermal conduction. In this compound, Ag atoms exhibit a dynamic duality that they are exclusively involved in intense low-lying transverse acoustic phonons while they also undergo local fluctuations inherent in an order-to-disorder transition occurring at 450 K. As a consequence of this extreme disorder-phonon coupling, transverse acoustic phonons become damped as approaching the transition temper…
Inorganic solid-state battery electrolytes show high ionic conductivities and enable the fabrication of all solid-state batteries. In this work, we present the temperature dependence of spin-lattice relaxation time (T1), spin-spin relaxation time (T2), and resonance linewidth of the 7Li nuclear magnetic resonance (NMR) for four solid-state battery electrolytes (Li3InCl6 (LIC), Li3YCl6 (LYC), Li1.48Al0.48Ge1.52(PO4)3 (LAGP) and LiPS5Cl (LPSC)) from 173 K to 403 K at a 7Li resonance frequency of 233 MHz, and from 253 K to 353 K at a 7Li resonance frequency of 291 MHz. Additionally, we measured t…
The effect of alternating shear orientation during cyclic loading on the relaxation dynamics in disordered solids is examined using molecular dynamics simulations. The model glass was initially prepared by rapid cooling from the liquid state and then subjected to cyclic shear along a single plane or periodically alternated in two or three dimensions. We showed that with increasing strain amplitude in the elastic range, the system is relocated to deeper energy minima. Remarkably, it was found that each additional alternation of the shear orientation in the deformation protocol brings the glass …
In this paper, an enthalpy-based multiple-relaxation-time (MRT) lattice Boltzmann (LB) method is developed for solid-liquid phase change heat transfer in metal foams under local thermal non-equilibrium (LTNE) condition. The enthalpy-based MRT-LB method consists of three different MRT-LB models: one for flow field based on the generalized non-Darcy model, and the other two for phase change material (PCM) and metal foam temperature fields described by the LTNE model. The moving solid-liquid phase interface is implicitly tracked through the liquid fraction, which is simultaneously obtained when t…
Paramagnetic defects in diamond and hexagonal boron nitride possess a unique combination of spin and optical properties that make them prototypical solid-state qubits. Despite the coherence of these spin qubits being critically limited by spin-phonon relaxation, a full understanding of this process is not yet available. Here we apply ab initio spin dynamics simulations to this problem and quantitatively reproduce the experimental temperature dependence of spin relaxation time and spin coherence time. We demonstrate that low-frequency two-phonon modulations of the zero-field splitting are respo…
Spin relaxation and decoherence is at the heart of spintronics and spin-based quantum information science. Currently, theoretical approaches that can accurately predict spin relaxation of general solids including necessary scattering pathways and capable for ns to ms simulation time are urgently needed. We present a first-principles real-time density-matrix approach based on Lindblad dynamics to simulate ultrafast spin dynamics for general solid-state systems. Through the complete first-principles descriptions of pump, probe and scattering processes including electron-phonon, electron-impurity…
We derive a formula for the electrical conductivity of solids that includes relaxation, dissipation, and quantum coherence. The derivation is based on the Kubo formula, with a Mori memory function approach to include dissipation effects at all orders in the relaxation interaction. It offers a practical method to evaluate the conductivity with electronic-structure codes and avoids the complications and limitations of the Kubo formula in the thermodynamic limit. The derivation of our formula provides a method applicable to other transport coefficients and correlation functions.
We combine hydrodynamic and field theoretic methods to develop a general theory of phonons as Goldstone bosons in crystals, glasses and liquids based on non-affine displacements and the consequent Goldstones phase relaxation. We relate the conservation, or lack thereof, of specific higher-form currents with properties of the underlying deformation field -- non-affinity -- which dictates how molecules move under an applied stress or deformation. In particular, the single-valuedness of the deformation field is associated with conservation of higher-form charges that count the number of topologic…
The disordered pyrochlore oxide Dy$_{2}$Zr$_{2}$O$_{7}$ shows the signatures of field-induced spin freezing with remnant zero-point spin-ice entropy at 5 kOe magnetic field. We have performed zero-field and longitudinal field Muon spin relaxation ($μ$SR) studies on Dy$_{2}$Zr$_{2}$O$_{7}$. Our zero field studies reveal the absence of both long-range ordering and spin freezing down to 62 mK. The $μ$SR relaxation rate exhibits a temperature-independent plateau below 4 K, indicating a dynamic ground state of fluctuating spins similar to the well-known spin ice system Dy$_{2}$Ti$_{2}$O$_{7}$. The …
We discuss the dynamical polarization, plasmon dispersion, relaxation time, and the Friedel oscillation of screened potential of the two-dimension Dirac and three-dimension Weyl system (which are gapped) in the low-energy tigh-binding model. The results, like the Fermi wavevector, Thomas-Fermi wavevector, and longitudinal conductivity are obtained in different dimensions. Some important conclusions are detailedly discussed in this paper, including the screening character under short or long range Coulomb interaction, and the longitudinal conductivity in two- or three-dimensions. The longitudin…
The understanding of the characteristics of a magnetic layer in a different environment is crucial for any spintronics application. Before practical applications, thorough scrutiny of such devices is compulsory. Here we study such a potential Hall device of MgO-capped Hf/GdFeCo bilayer (FeCo-rich) for magnetization relaxation around nucleation fields at different voltage probe line widths and dc sensing currents. The device is characterized by anomalous Hall measurements in transverse and longitudinal Hall geometries for two different probe widths A (5 micrometer) and B (1 micrometer). The coe…
Hydrogen induced nonmonotonic relaxation in binary mixtures similar to Pd-Er alloys as a transition process in nonequilibrium heterogeneous systems with spinodal decomposition
We present an experimental and theoretical study of the longitudinal electron spin relaxation ($T_1$) of shallow donors in the direct band-gap semiconductor ZnO. $T_1$ is measured via resonant excitation of the Ga donor-bound exciton. $T_1$ exhibits an inverse-power dependence on magnetic field $T_1\propto B^{-n}$, with $4\leq n\leq 5$, over a field range of 1.75 T to 7 T. We derive an analytic expression for the donor spin-relaxation rate due to spin-orbit (admixture mechanism) and electron-phonon (piezoelectric) coupling for the wurtzite crystal symmetry. Excellent quantitative agreement is …
The spin dynamics of the strongly localized, donor-bound electrons in fluorine-doped ZnSe epilayers is studied by pump-probe Kerr rotation techniques. A method exploiting the spin inertia is developed and used to measure the longitudinal spin relaxation time, $T_1$, in a wide range of magnetic fields, temperatures, and pump densities. The $T_1$ time of the donor-bound electron spin of about 1.6 $μ$s remains nearly constant for external magnetic fields varied from zero up to 2.5 T (Faraday geometry) and in a temperature range $1.8-45$ K. The inhomogeneous spin dephasing time, $T_2^*=8-33$ ns, i…
We report filling-fraction dependent dielectric spectroscopy measurements on the relaxation dynamics of the rod-like nematogen 7CB condensed in 13 nm silica nanochannels. In the film-condensed regime, a slow interface relaxation dominates the dielectric spectra, whereas from the capillary-condensed state up to complete filling an additional, fast relaxation in the core of the channels is found. The temperature-dependence of the static capacitance, representative of the averaged, collective molecular orientational ordering, indicates a continuous, paranematic-to-nematic (P-N) transition, in con…
