Investigations of half-metallic ferromagnetism and thermoelectric properties of cubic XCrO3 (X = Ca,Sr,Ba) compounds via first-principles approaches

In this paper, the physical aspects of the cubic phase XCrO₃ ($\mathrm{X}=\mathrm{Ca},\mathrm{Sr},\mathrm{Ba}$) perovskites are studied by employing full-potential linearized augmented plane wave plus local orbital ($\text{FP-LAPW}+\mathit{lo}$) method. These compounds have been found stable in ferromagnetic (FM) phase since they possess lower energy in FM phase compared to non-FM phase and their stability is also confirmed by calculating the enthalpy of formation (ΔH). The electronic structures of these compounds are analyzed with Trans and Blaha modified Becke–Johnson potential (TB-mBJ) for both spin up and spin down channels, which indicate their half-metallic characters. Analysis of density of states (DOS) shows major contributions of O-2p states in the valence band and Cr 3d-state in conduction band. A comparative analysis of crystal field effect ($\mathrm{\Delta }{\mathrm{E}}_{\mathrm{crystal}}$) and the exchange energies (direct ${\mathrm{\Delta }}_x(d)$ and indirect ${\mathrm{\Delta }}_x(pd)$) tells about the main part of electronic spin in ferromagnetic character. The calculated magnetic moments make these compounds favorable for spintronic applications. In the end, thermoelectric parameters are computed for 200 K–800 K temperature range to explore potential of these compounds for applications in renewable energy devices.     

Nonlinear integral equations for the finite size effects of RSOS and vertex-models and related quantum field theories

Starting from critical RSOS lattice models with appropriate inhomogeneities, we derive two component nonlinear integral equations to describe the finite volume ground state energy of the massive ${\varphi }_{\mathrm{id},\mathrm{id},\mathrm{adj}}$ perturbation of the $\mathit{SU}{(2)}_k\times \mathit{SU}{(2)}_{k^{\prime }}/\mathit{SU}{(2)}_{k+k^{\prime }}$ coset models. When $k^{\prime }\to \infty$ while the value of k is fixed, the equations correspond to the current–current perturbation of the $\mathit{SU}{(2)}_k$ WZW model. Then modifying one of the kernel functions of these equations, we propose two component nonlinear integral equations for the fractional supersymmetric sine-Gordon models. The lattice versions of our equations describe the finite size effects in the corresponding lattice models, namely in the critical $\mathrm{RSOS}(k,q)$ models, in the isotropic higher-spin vertex models, and in the anisotropic higher-spin vertex models. Numerical and analytical checks are also performed to confirm the correctness of our equations. These type of equations make it easier to treat the excited state problem.