Вклад распределенного эффекта Пельтье в эффективность ветви термоэлектрического охладителя

An attempt is made to calculate the contribution of the distributed Peltier effect to the efficiency of the branch of the thermoelement Z for various types of impurity distribution. For this purpose, the boundary problem of thermal balance in the branch of the thermoelectric element was solved numerically, taking into account the distributed Peltier effect. The case of non-degenerate charge carriers was considered within the framework of the standard two-band model. The parameters of charge carriers were selected close to thermoelectrics based on bismuth and antimony tellurides. As the calculation in the framework of the two-zone model showed, the use of the distributed Peltier effect leads only to partial absorption of Joule heat, which contributes to an increase in the overall efficiency of the branch. In this case, the Z parameter along a significant part of the branch takes values significantly less than the maximum value

Character of Doped Holes in Nd1−xSrxNiO2

We investigate charge distribution in the recently discovered high-Tc superconductors, layered nickelates. With increasing value of charge-transfer energy, we observe the expected crossover from the cuprate to the local triplet regime upon hole doping. We find that the d−p Coulomb interaction Udp makes Zhang-Rice singlets less favorable, while the amplitude of local triplets at Ni ions is enhanced. By investigating the effective two-band model with orbitals of x2−y2 and s symmetries we show that antiferromagnetic interactions dominate for electron doping. The screened interactions for the s band suggest the importance of rare-earth atoms in superconducting nickelates.

An elementary proof and detailed investigation of the bulk-boundary correspondence in the generic two-band model of Chern insulators

With the inclusion of arbitrary long-range hopping and (pseudo)spin–orbit coupling amplitudes, we formulate a generic model that can describe any two-dimensional two-band bulk insulators, thus providing a simple framework to investigate arbitrary adiabatic deformations upon the systems of any arbitrary Chern numbers. Without appealing to advanced techniques beyond the standard methods of solving linear difference equations and applying Cauchy’s integral formula, we obtain a mathematically elementary yet rigorous proof of the bulk-boundary correspondence on a strip, which is robust against any adiabatic deformations upon the bulk Hamiltonian and any uniform edge perturbation along the edges. The elementary approach not only is more transparent about the underlying physics but also reveals various intriguing nontopological features of Chern insulators that have remained unnoticed or unclear so far. Particularly, if a certain condition is satisfied (as in most renowned models), the loci of edge bands in the energy spectrum and their (pseudo)spin polarizations can be largely inferred from the bulk Hamiltonian alone without invoking any numerical computation for the energy spectrum of a strip.