arXiv subjects

Moumita Indra

Publications and source records attributed to Moumita Indra.

9 recordsLinked to original sources

arXiv2026

Valley polarization dependence of candidate even-denominator fractional quantum Hall states in monolayer graphene

We investigate even-denominator fractional quantum Hall (EDFQH) states in monolayer graphene, focusing on the experimentally observed filling fractions $\nu = 1/2$ and $\nu = 1/4$. Owing to the approximate SU(4) symmetry arising from spin and valley degrees of freedom, graphene hosts a rich variety of multi-component fractional quantum Hall states with different polarization configurations. Using the Chern-Simons composite fermion framework for SU(4) systems, we construct candidate variational wave functions corresponding to distinct spin, valley, and mixed polarization states. The ground-state energies of these states are evaluated numerically using the Coulomb interaction in spherical geometry. By comparing energies across different polarization sectors, we identify the energetically favored configurations at $\nu = 1/2$ and $\nu = 1/4$. Our variational energy comparison suggests that the energetically favored candidate states correspond to multi-component correlated quantum Hall liquids. Within the restricted family of trial states considered here, these states differ from a simple composite-fermion Fermi-sea description. These findings provide insight into the role of valley polarization and SU(4) symmetry in stabilizing even-denominator fractional quantum Hall states in graphene.

cond-mat.str-el↗

arXiv2025

Collective excitation spectra of dipolar bosonic fractional quantum Hall states

We numerically investigate the collective excitation of spin-conserving and spin-reversed configuration of rotating diluted ultra-cold dipolar Bose gas. Rotating trapped Bose gas produces a fictitious magnetic field perpendicular to the trapping harmonic potential, which exhibits strongly correlated fractional quantum Hall states. We consider the long-range dipole-dipole interaction and compute the low lying excitations spectrum for the three fractions of the first Jain series $\nu = 1/2, 1/4, 1/6$. We find that for both the spin-conserving and spin-reversed excitation the gap between the fundamental mode and the higher excitation mode increases upon increase in the filling fraction. The fundamental modes and the next higher-energy mode of excitation spectra for each of the three fractions show the presence of double roton for spin-conserving configuration only. Finally we complement our observation by calculating the spectral weight for the fundamental mode of excitation spectra which show the momenta at which the spectral weight exhibits the maxima shifts towards the lower momenta for both the excitations. Our observation for the spectral weight could be related with the inelastic Raman scattering which may be useful for the future experimental study to detect the excitation in ultracold system.

cond-mat.quant-gas↗

arXiv2023

Collective excitation of bosonic quantum Hall state

The recent developments in the theory of rapidly rotating Bose atoms have been reviewed in this article. Rotation leads to the development of quantized-vortices, that cluster into a vortex array, exactly to how superfluid helium behaves. Theoretically, a number of strongly correlated phases are projected to exist in this domain, which might be thought of as bosonic counterparts of fractional quantum Hall effect (FQHE). It is now possible for bosons associating with a short-range interaction to exhibit a FQHE, because the system of neutral bosons in a fast rotating atomic trap is analogous to charged bosons placed in a fictitious magnetic field. The neutral collective spin-conserving and spin-flip excitation for the rotating ultra-cold dilute Bose atoms in the FQHE domain are being discussed. We have introduced a realistic interaction between the Bose particles together with long-range interaction and presented a short review article about various fractional quantum Hall states and their spin conserving and spin reversed collective modes.

cond-mat.quant-gas↗

arXiv2023

Double roton-minima in bosonic fractional quantum Hall states

We have studied the collective spin-conserving collective excitation spectra in rotating diluted ultra-cold Bose atoms. Double roton-minima have been observed in the fractional quantum Hall (FQH) states for the two filling fractions ($ν$) of the first series of Jain's composite fermion sequences. The obtained roton-minima for $ν$ = 1/4 are at the wave-vectors 1.26 and 2.38 and the roton-minima for $ν$ = 1/6 have been shifted to 1.08 and 2.06. Such shift of roton-minima is attributed due to strong correlation between the particles in bosonic FQH-system. Moreover, the number of roton minima observed depends upon number of attached fluxes as well as the ranges of interaction between the particles.

cond-mat.mes-hall↗

arXiv2023

Analytical study of ion-acoustic solitary waves in a magnetized plasma with degenerate electrons

The propagation of fully nonlinear ion acoustic solitary waves (IASW) in a magneto-plasma with degenerate electrons was investigated by Abdelsalam et al. [[1] Physics Letters A 372 (2008) 4923]. Based on their work in the present work, a rigorous and general analytical study is presented. This confirms their implied assumption that (i) only hump and no cavity is possible and (ii) for humps, the algebraic equation for the maximum density N obtained by them determines it uniquely (naturally assumes N > 1). Here we confirm analytically their assertion that N decreases with lx (the direction cosine of the wave vector k along the x-axis) and N increases with the increase of the Mach number (M).

physics.plasm-ph↗

arXiv2022

Higher energy modes of Fractional quantum Hall Effect

We have calculated the energy spectra for almost all the filling fractions in the Jain series low energy fundamental mode as well as higher energy modes using composite fermion theory. The nature of the low energy mode and higher energy mode is nearly identical to the roton mode. We have observed that, these series of filling fractions $ν=\frac{n}{2pn+1}$ possess $n$ number of roton minima in their higher energy mode.

cond-mat.str-el↗

arXiv2022

Study of polarization of even-denominator fractional quantum Hall states in SU(4) Graphene

We have focussed to study the even-denominator fractional quantum Hall (EDFQH) states observed in monolayer graphene. In this letter, we have studied polarization mainly for the two EDFQH states at filling fractions $\nu = 1/2, 1/4$, which are observed in an experimental study [Nat. Phys. 14, 930 (2018)] a few years ago. We have applied Chern Simon's gauge field theory to explain the possible variational wave functions for different polarized states and calculated their ground state energies using the Coulomb potential. We have chosen the lowest energy states using suitable combinations of flux attached with the electrons for different polarized states of those EDFQH states.

cond-mat.str-el↗

arXiv2019

Collective spin density excitations of fractional quantum Hall states in dilute ultracold Bose atoms

We have studied collective spin density excitations of fractional quantum Hall effect (FQHE) in rotating Bose-Einstein condensation for the three filling fractions of first series of Jain's composite fermion sequences. We have considered, short-ranged contact interactions between the Bose atoms as well as long range Coulomb interactions to compare the nature of the spectras with FQHE of electrons. Using Monte Carlo method for finite but large number of particles, the lowest order collective modes of spin-reversed sectors is calculated here, by computing the energy differences of the respective excitons from the fully polarized ground states.

cond-mat.mes-hall↗

arXiv2018

Study of partially polarized fractional quantum Hall states

We have studied the partially spin-polarized fractional quantum Hall states using Chern Simon's theory and plasma picture proposed by Halperin. Using these theoretical techniques we have tried to find the stable polarized states of different filling fractions observed in experiments. We have calculated the ground state energies of those states and also pair correlation function. We have described the nature of the states by the behaviour of this quantity. In our study, we have seen that the partially polarized states, which do not fit with Jain's composite fermion description are basically the mixed state of up-spin liquid phase and down-spin solid phase.

cond-mat.mes-hall↗