Journal of Physics. Condensed Matter : An Institute of Physics Journal

We present an order-N quantum transport calculation methodology to evaluate thermoelectric transport coefficients, such as electric conductivity and Seebeck coefficient. Different from a conventional method using the electric conductivity spectrum, it obtains the coefficients directly from the correlation function between heat and electric current based on linear response theory. As an example, we apply the methodology to a two-dimensional square-lattice model with static disorder and confirm that the calculated results are consistent with those obtained by the conventional method...

The model of an ideal polymer chain in a harmonic applied field has broad applicability in situations involving polymer confinement and deformation due to applied stress. In this work we (1) formulate a general analytical model for a continuous Gaussian chain under a harmonic applied potential and (2) evaluate the statistical mechanics of this model given the potential, obtaining partition functions and moment generating functions that describe the chain configurations. Closed-form expressions for the squared radius of gyration, potential energy, partition function, and moment generating function for the center of mass are obtained for a general and multidimensional harmonic field...

In this article we demonstrate that dynamical quantum phase transitions occur for an exemplary higher order topological insulator, the Benalcazar-Bernevig-Hughes model, following quenches across a topological phase boundary. A dynamical bulk boundary correspondence is also seen both in the eigenvalues of the Loschmidt overlap matrix and the boundary return rate. The latter is found from a finite size scaling analysis for which the relative simplicity of the model is crucial. Contrary to the usual two dimensional case the dynamical quantum phase transitions in this model show up as cusps in the return rate, as for a one dimensional model, rather than as cusps in its derivative as would be typical for a two dimensional model...

Spin reorientation transition is an ubiquitous phenomenon observed in magnetic rare earth orthferrites RFeO3, which has garnered significant attention in recent years due to the potential applications in spintronics or magnetoelectric devices. Although a plenty of experimental works suggest that the magnetic interaction between R3+ and Fe3+ spins is at the heart of the spin reorientation, but a direct and decisive support from theoretical side is lacking so far, owning to the tricky handling of R 4f electrons...

Modulation of the electronic structure has played a crucial role in advancing the field of two-dimensional materials, but there are still many unexplored directions, such as the twist angle for a novel degree of freedom, for modulating the properties of heterostructures. We observed a distinct pattern in the energy bands of bilayer bismuthene, demonstrating that modulating the twist angle and interlayer spacing significantly influences interlayer interactions. Our study of various interlayer spacings and twist angles revealed a close relationship between bandgap size and interlayer spacing, while the twist angle notably affects the shape of the energy bands...

Resonant exchange of the chiral Majorana fermions (MFs) that is coupled to two parallel Majorana zero
modes (MZMs) or two parallel quantum dots (QDs) is investigated. We find that, in the two QDs coupling
case, the resonant exchange for the chiral MFs is analogous to that in the MZM coupling case. We further
propose a circuit based on topological superconductor (TSC), which is formed by the proximity coupling of
a quantum anomalous Hall insulator (QAHI) and a s-wave superconductor, to observe the resonant exchange
of chiral MFs pairs...

The electrical conduction mechanisms for bulk samples of In0.1Se0.9-xSbx (x= 0, 0.04, 0.08 and 0.12) nano-chalcogenide system, synthesized by the melt-quenching technique are investigated through current-voltage (I-V) characteristics. For the detailed study of conduction mechanism pellets of bulk samples are prepared. A thorough examination of electrical conductivity is done in the temperature range of 295-318 K and 0-50 V voltage range. From I-V measurements it is observed that samples are showing ohmic nature at lower field and non-ohmic nature at relatively higher field values...

We performed small-angle X-ray scattering measurements of liquid Te using a synchrotron radiation facility and observed maximum scattering intensity near 620 K in the supercooled region (melting temperature 723 K). This indicates that density inhomogeneity exists in liquid Te, and the fact that this temperature coincides with the temperature at which the specific heat, sound velocity, and thermal expansion coefficient reach their maxima means that this density inhomogeneity is the cause of these thermodynamic anomalies...

This work comprehensively investigates the non-Hermitian skin effect (NHSE) in a spinless Bernevig- Hughes-Zhang (BHZ)-like model in one dimension. It is generally believed that a system with non-reciprocal hopping amplitudes demonstrates NHSE. However, we show that there are exceptions, and more in-depth analyses are required to decode the presence of NHSE or its variants in a system. The fascinating aspects of our findings, depending on the inclusion of non-reciprocity in the inter-orbital hopping terms, concede the existence of conventional NHSE or NHSE at both edges and even a surprising absence of NHSE...

Two-Temperature molecular dynamics (2T-MD) is a common approach for describing how electrons contribute to the evolution of a damage cascade by addressing their role in the redistribution of energy in the system. However, inaccuracies in 2TMD's treatment of the high-energy particles have limited its utilisation. Here, we propose a reformulation of the traditional 2T-MD scheme to overcome this limitation by addressing the spurious double-interaction of high-energy atoms with electrons. We conduct a series of radiation damage cascades for 30, 50, and 100 keV primary knock-on atoms (PKA) in increasingly large cubic W cells...

Graphene has attracted wide attentions since its successfully exfoliation. Honeycomb sp2 carbon lattice and Dirac semi-metal band structure make graphene a promising material with excellent mechanical strength, thermal conductivity, and carrier mobility. However, the absence of intrinsic bandgap limits its application in semiconductor. Defects in graphene is supposed to modify its band structure and lead to an opened bandgap. Many methods have been demonstrated to introduce defects into graphene, such as chemical reaction, plasma, electron beam, and laser...

Inelastic x-ray scattering (IXS) experiments on liquid sulphur were carried out below (140◦C) and above (180◦C) the polymerisation temperature Tλ of about 159◦C to investigate changes in the collective dynamics of this unique liquid, that exhibits a liquid‒liquid transition. As reported earlier, broad longitudinal acoustic excitation signals were observed at both temperatures, and only the width of the quasielastic peaks slightly decreased when the temperature crossed the transition temperature...

Anisotropic lattice deformation plays an important role in the quantum mechanics of solid state physics. The possibility of mediating the competition and cooperation among different order parameters by applying in situ strain/stress on quantum materials has led to discoveries of a variety of elasto-quantum effects on emergent phenomena. It has become increasingly critical to have the capability of combining the in situ strain tuning with X-ray techniques, especially those based on synchrotrons, to probe the microscopic elasto-responses of the lattice, spin, charge, and orbital degrees of freedom...

Thermal energy storage using phase change materials has great potential to reduce the weather dependency of sustainable energy sources. However, the low thermal conductivity of most phase change materials is a long-standing bottleneck for large-scale practical applications. In modifications to increase the thermal conductivity of phase change materials, the interfacial thermal resistance between phase change materials and discrete additives or porous networks reduces the effective thermal energy transport. In this work, we investigated the interfacial thermal resistance between a metal (gold) and a polyol solid-liquid phase change material (erythritol) at various temperatures including temperatures below the melting point (300 and 350 K), near the melting point (390, 400, 410 K, etc...

The research for lead-free magnetoelectric multiferroic composite materials has increased considerably because theysynthesis with lead-free arephase environmentally friendly. For compositeshas proven challenging to obtain high with 0-3 connectivity,values of magnetoelectric coupling. This work reports the successful synthesis of the KNN/CFO composite (K0.5N0.5NbO3/CoFe2O4) by conventional synthesis process. XRD and SEI showed two well-defined, also presenting good electric polarization values. The magnetoelectric coefficient was very high, reaching values close to 2850 mV/cm...

Rare-earth A 2 Zr2 O7 zirconates have attracted considerable attention of the scientific community for their complex magnetic, electronic and material properties applicable in modern technologies. Light rare-earth members of the series, crystallising in the so-called pyrochlore variant of cubic crystal structure, have been studied in detail. Heavier A 2 Zr2 O7 compounds have been investigated mainly from the material properties viewpoint, focussing on their thermal properties and stability at high temperature and pressure...

We have developed an approach for predicting trends for efficient hot carrier generation among disordered metal alloys. We provide a simple argument for the importance of indirect transitions in the presence of disorder, thus justifying the use of Joint Density of States (JDOS)-like quantities for exploring these trends. We introduce a new JDOS-like quantity, JDOSK, which heuristically incorporates differences in particle lifetimes depending on their excitation energies. To demonstrate the efficacy of this new quantity, we apply it to the study of Cu50X50 where X = Ag, Au, Pd and Y50Pd50 where Y = Au, Ni...

In this work we report magnetic properties of the orthorhombic perovskite
Lu0.9Sr0.1Cr0.5Fe0.5O3 synthesized by a wet chemical method. As in LuCr0.5Fe0.5O3 the compound
with Sr shows the magnetization reversal phenomenon, but the magnetic order and the compensation
temperature occur at higher temperatures. Interestingly, in M vs H curves a hysteresis loop is observed
when Cr4+ and Cr3+ ions coexist as a consequence of the aliovalent substitution of Lu3+ by Sr2+ in the
B sites of the perovskite...

Spin caloritronics, a research field studying on the interconversion between a charge current ( J c ) and a heat current ( J q ) mediated by a spin current ( J s ) and/or magnetization ( M ), has attracted much attention not only for academic interest but also for practical applications. Newly discovered spin-caloritronic phenomena such as the spin Seebeck effect (SSE) have stimulated the renewed interest in the thermoelectric phenomena of a magnet, which have been known for a long time, e.g. the anomalous Nernst effect (ANE)...

Today's thermodynamics is largely based on the combined law for equilibrium systems and statistical mechanics derived by Gibbs in 1873 and 1901, respectively, while irreversible thermodynamics for nonequilibrium systems resides essentially on the Onsager Theorem as a separate branch of thermodynamics developed in 1930s. Between them, quantum mechanics was invented and was quantitatively solved in terms of density functional theory (DFT) in 1960s. These three scientific domains operate based on different principles and are very much separated from each other...