arXiv subjects

S. P. Shukla

Publications and source records attributed to S. P. Shukla.

2 recordsLinked to original sources

arXiv1999

Large Skyrmions in an Al(0.13)Ga(0.87)As Quantum Well

We report tilted-field magnetotransport measurements of two-dimensional electron systems in a 200 Angstrom-wide Al(0.13)Ga(0.87)As quantum well. We extract the energy gap for the quantum Hall state at Landau level filling ν=1 as a function of the tilt angle. The relatively small effective Lande g-factor (g ~ 0.043) of the structure leads to skyrmionic excitations composed of the largest number of spins yet reported (s ~ 50). Although consistent with the skyrmion size observed, Hartree-Fock calculations, even after corrections, significantly overestimate the energy gaps over the entire range of our data.

cond-mat.mes-hall↗

arXiv1998

Magnetic Anisotropy in Quantum Hall Ferromagnets

We show that the sign of magnetic anisotropy energy in quantum Hall ferromagnets is determined by a competition between electrostatic and exchange energies. Easy-axis ferromagnets tend to occur when Landau levels whose states have similar spatial profiles cross. We report measurements of integer QHE evolution with magnetic-field tilt. Reentrant behavior observed for the $ν= 4$ QHE at high tilt angles is attributed to easy-axis anisotropy. This interpretation is supported by a detailed calculation of the magnetic anisotropy energy.

cond-mat.mes-hall↗