186 citations · 896 across the 35 of their papers we have counts for
25 papers · 1 filter
Low-temperature theory of inversion and quantum oscillations in Kondo insulators
Arnav Pushkar, Brijesh Kumar
The half-filled Kondo lattice model is studied at low temperatures on simple cubic lattice using the self-consistent theory developed in Phys. Rev. B 96, 075115 (2017). It is found…
Quantum paramagnetism and magnetization plateaus in a kagome-honeycomb Heisenberg antiferromagnet
Meghadeepa Adhikary, Arnaud Ralko, Brijesh Kumar
A spin-1/2 Heisenberg model on honeycomb lattice is investigated by doing triplon analysis and quantum Monte Carlo calculations. This model, inspired by Cu(pymca)(ClO),…
Inversion and magnetic quantum oscillations in symmetric periodic Anderson model
Panch Ram, Brijesh Kumar
We study the symmetric periodic Anderson model of the conduction electrons hybridized with the localized correlated electrons on square lattice. Using the canonical representation…
Phase diagram of the Hubbard-Kondo lattice model from variational cluster approximation
J. P. L. Faye, M. N. Kiselev, P. Ram +2
The interplay between the Kondo effect and magnetic ordering driven by the Ruderman-Kittel-Kasuya-Yosida interaction is studied within the two-dimensional Hubbard-Kondo lattice mod…
Spontaneous dimerization and moment formation in the Hida model of spin-1 kagomé antiferromagnet
Pratyay Ghosh, Brijesh Kumar
The Hida model, defined on honeycomb lattice, is a spin-1/2 Heisenberg model of aniferromagnetic hexagons (with nearest-neighbor interaction, ) coupled via ferromagnetic bon…
Level crossings induced by a longitudinal coupling in the transverse field Ising chain
Grégoire Vionnet, Brijesh Kumar, Frédéric Mila
We study the effect of antiferromagnetic longitudinal coupling on the one-dimensional transverse field Ising model with nearest-neighbour couplings. In the topological phase where,…
Theory of Quantum Oscillations of Magnetization in Kondo Insulators
Panch Ram, Brijesh Kumar
The Kondo lattice model of spin-1/2 local moments coupled to the conduction electrons at half-filling is studied for its orbital response to magnetic field on bipartite lattices. T…
Quantum to classical transition in the ground state of a spin- quantum antiferromagnet
Bimla Danu, Brijesh Kumar
We study a frustrated spin- staggered-dimer Heisenberg model on square lattice by using the bond-operator representation for quantum spins, and investigate the emergence of clas…
Intertwined nematic orders in a frustrated ferromagnet
Yasir Iqbal, Pratyay Ghosh, Rajesh Narayanan +3
We investigate the quantum phases of the frustrated spin- -- Heisenberg model on the square lattice with ferromagnetic and antiferromagnetic …
Plaquette-triplon analysis of magnetic disorder and order in a trimerized spin-1 Kagomé antiferromagnet
Pratyay Ghosh, Akhilesh Kumar Verma, Brijesh Kumar
A spin-1 Heisenberg model on trimerized Kagomé lattice is studied by doing a low-energy bosonic theory in terms of plaquette-triplons defined on its triangular unit-cells. The mode…
Effective models for the magnetization behavior of Shastry-Sutherland model
Brijesh Kumar, Bimla Danu
The minimal effective model for the magnetisation plateaus below 1/2 in the Shastry-Sutherland model is derived to be an Ising model of certain unit-cell hard-core bosons with anis…
Quantum Ising dynamics and Majorana-like edge modes in the Rabi lattice model
Brijesh Kumar, Somenath Jalal
The atomic dipoles in the Rabi lattice model exhibit quantum Ising dynamics in the limit of strong atom-photon interaction. It governs the para- to ferro-electric phase transition…
DMRG studies on linear-exchange quantum spin models in one dimension
Bimla Danu, Brijesh Kumar, Ramesh V. Pai
We study a class of spin-1/2 quantum antiferromagnetic chains using DMRG technique. The exchange interaction in these models decreases linearly as a function of the separation betw…
Exact spin-orbital separation in a solvable model in one dimension
Brijesh Kumar
A one-dimensional model of coupled spin-1/2 spins and pseudospin-1/2 orbitals with nearest-neighbor interaction is rigorously shown to exhibit spin-orbital separation by means of a…
Triplon mean-field analysis of an antiferromagnet with degenerate Shastry-Sutherland ground states
Rakesh Kumar, Brijesh Kumar
We look into the quantum phase diagram of a spin- antiferromagnet on the square lattice with degenerate Shastry-Sutherland ground states, for which only a schematic ph…
Bond-operators and triplon analysis for spin-S dimer antiferromagnets
Brijesh Kumar
The mean-field triplon analysis is developed for spin-S quantum antiferromagnets with dimerized ground states. For the spin-1/2 case, it reduces to the well known bond-operator mea…
Honeycomb antiferromagnet with a triply degenerate dimer ground state
Rakesh Kumar, Dushyant Kumar, Brijesh Kumar
We present an antiferromagnetic quantum spin-1/2 model on honeycomb lattice. It has two parts, one of which is the usual nearest-neighbor Heisenberg model. The other part is a cert…
Exact solution of the infinite-U Hubbard problem and other models in one dimension
Brijesh Kumar
An interacting spin-fermion model is exactly solved on an open chain. In a certain representation, it is the nearest-neighbor Hubbard model in the limit of infinite (local inte…
Canonical representation for electrons and its application to the Hubbard model
Brijesh Kumar
A new representation for electrons is introduced, in which the electron operators are written in terms of a spinless fermion and the Pauli operators. This representation is canonic…
Fourfold degenerate columnar-dimer ground state in square lattice antiferromagnets
Rakesh Kumar, Brijesh Kumar
We construct and study two frustrated quantum spin-1/2 models on square lattice, which are like the antiferromagnetic - model with some additional four-spin exchange inte…
Absence of single particle Bose-Einstein condensation at low densities for bosons with correlated-hopping
Rachel Bendjama, Brijesh Kumar, Frederic Mila
Motivated by the physics of mobile triplets in frustrated quantum magnets, the properties of a two dimensional model of bosons with correlated-hopping are investigated. A mean-fiel…
Two quantum spin models on the checkerboard lattice with an exact two-fold degenerate Shastry-Sutherland ground state
Brijesh Kumar
Two quantum spin models with bilinear-biquadratic exchange interactions are constructed on the checkerboard lattice. It is proved that, under certain sufficient conditions on the e…
Superconductivity in CoO Layers and the Resonating Valence Bond Mean Field Theory of the Triangular Lattice t-J model
Brijesh Kumar, B. Sriram Shastry
Motivated by the recent discovery of superconductivity in two dimensional CoO layers, we present some possibly useful results of the RVB mean field theory applied to the triang…
Quantum spin models with exact dimer ground states
Brijesh Kumar
Inspired by the exact solution of the Majumdar-Ghosh model, a family of one-dimensional, translationally invariant spin hamiltonians is constructed. The exchange coupling in these…