arXiv subjects

Kaushal Kumar Kesharpu

Publications and source records attributed to Kaushal Kumar Kesharpu.

5 recordsLinked to original sources

arXiv2025

A method to treat strongly correlated topological superconductors in one and two dimensions

In the strong electron-electron (e-e) interaction limit each atomic site is constrained to be either empty or singly occupied. One can treat this scenario by fractionalizing the electrons into spin and charge degrees of freedom. We use the coherent state symbols associated with the lowest irreducible representation of the $su(2|1)$ superalgebra spanned by the Hubbard operators to solve the proposed models, as they implicitly take into account both the single particle occupation constraint and the fractionalization of the electrons. As an example, using the proposed method we solve the one dimensional Kitaev chain and two-dimensional BCS-Hubbard model to show the emergence of topological properties. The proposed procedure is quite general and can be used to analyze different lattice Hamiltonian, provided strong e-e correlation excludes doubly occupied states.

cond-mat.str-el↗

arXiv2025

Re-entrant topological order in strongly correlated nanowire due to Rashba spin-orbit coupling

The effect of the Rashba spin orbit coupling (RSOC) on the topological properties of the one-dimensional (1D) extended $s$-wave superconducting Hamiltonian, in the presence of strong electron-electron correlation, is investigated. It is found that a non-zero RSOC increases the periodicity of the effective Hamiltonian, which results in the folding of the Brillouin zone (BZ), and consequently in the emergence of an energy gap at the boundary of the BZ. Essentially the initial single band is divided into number of sub-bands. If the chemical potential lies inside the energy gaps (sub-bands) then the phase is topologically trivial (non trivial). This is the origin of re-entrant nature of the existent topological properties. The emergence of sub-bands allows us to drive the system in and out of the topological phase by the proper tuning of the chemical potential. A heterostructure involving van der Waals materials and a 1D Moire pattern for an investigation of the predicted effect has also been proposed. We also discuss how in-plane magnetic field can be used to control the RSOC coupling and induced periodicity in depleted InAs nanowire in which evidence of strong electron-electron correlation has been found.

cond-mat.str-el↗

arXiv2024

A proposal for realizing Majorana fermions without external magnetic field in strongly correlated nanowires

We show that one dimensional (1D) topological superconductivity can be placed in the context of phenomena associated with strongly correlated electron systems. Here we propose a system consisting of a one-dimensional chain of strongly correlated fermions placed on a superconducting (SC) substrate that exhibits a spin-singlet extended $s$-wave pairing. Strong electron correlation is shown to transform an extended $s$-wave SC into a topological SC that hosts Majorana fermions. In contrast to the approaches based on mean-field treatments, no Zeeman or exchange magnetic field is needed to produce such an effect.

cond-mat.supr-con↗

arXiv2023

Factors affecting the topological Hall effect in strongly correlated layered magnets: spin of the magnetic atoms, polar and azimuthal angle subtended by the spin texture

The Hamiltonian of a two dimensional (2D) magnetic material in the strong correlation regime with a spin texture, for which both azimuthal and polar angle changes, is solved using $su(2)$ path integral method. The dependence of the Chern number on the atomic spin ($S$), azimuthal angle ($\vec{q}_{1}$) and polar angle ($\vec{q}_{2}$) modulation vector of the spin texture on a bipartite honeycomb lattice is found. For $S \leq 3$ it was found that Chern number depends strongly on $\vec{q}_{2}$ and $S$. We discuss applicability of the model to several van der Waals magnets. Experimentally, it is expected that, with increase in spin modulation vector the sign of the topological Hall conductivity changes, $+σ_{xy}^{THE} \to -σ_{xy}^{THE}$ or vice-versa, when $S$ is constant. We also propose several heterostrucures for experimental realization of this effect.

cond-mat.mes-hall↗

arXiv2018

Temperature dependence of resistivity at the transition to a charge density wave state in rare-earth tritellurides

About a half of the Fermi surface in rare-earth tritellurides RT e3 becomes gapped below the transition to a charge-density-wave (CDW) state, as revealed by ARPES data. However, the observed jump in resistivity during the CDW transition is less than 20%. Previously this phenomenon was explained by hypothesizing a very slow evolution of CDW energy gap below transition temperature in RTe3 compounds, which contradicts the X-ray measurements. Here we show that this weak change in resistivity can be explained in the framework of standard mean-field temperature dependence of the CDW energy gap in agreement with X-ray data. The change of resistivity caused by CDW is weak because the decrease in conducting electron density at the Fermi level is almost compensated by the decrease in their scattering rate. We calculate resistivity in RTe3 compounds using the Boltzmann transport equation and the mean-field description of the CDW state, and obtain a good agreement with experimental data.

cond-mat.supr-con↗