arXiv subjects

Md. Shafayat Hossain

Publications and source records attributed to Md. Shafayat Hossain.

21 records · Page 2Linked to original sources

arXiv2016

Reorientation of the stripe Phase of 2D Electrons by a Minute Density Modulation

Interacting two-dimensional electrons confined in a GaAs quantum well exhibit isotropic transport when the Fermi level resides in the first excited ($N=1$) Landau level. Adding an in-plane magnetic field ($B_{||}$) typically leads to an anisotropic, stripe-like (nematic) phase of electrons with the stripes oriented perpendicular to the $B_{||}$ direction. Our experimental data reveal how a periodic density modulation, induced by a surface strain grating from strips of negative electron-beam resist, competes against the $B_{||}$-induced orientational order of the stripe phase. Even a minute ($<0.25\%$) density modulation is sufficient to reorient the stripes along the direction of the surface grating.

cond-mat.mes-hall↗

arXiv2016

Morphing of 2D Hole Systems at $ν=3/2$ in Parallel Magnetic Fields: Compressible, Stripe, and Fractional Quantum Hall Phases

A transport study of two-dimensional (2D) holes confined to wide GaAs quantum wells provides a glimpse of a subtle competition between different many-body phases at Landau level filling $ν=3/2$ in tilted magnetic fields. At large tilt angles ($θ$), an anisotropic, stripe (or nematic) phase replaces the isotropic compressible Fermi sea at $ν=3/2$ if the quantum well has a symmetric charge distribution. When the charge distribution is made asymmetric, instead of the stripe phase, an even-denominator fractional quantum state appears at $ν=3/2$ in a range of large $θ$, and reverts back to a compressible state at even higher $θ$. We attribute this remarkable evolution to the significant mixing of the excited and ground-state Landau levels of 2D hole systems in tilted fields.

cond-mat.mes-hall↗

arXiv2014

Self-consistent Capacitance-Voltage Characterization of Gate-all-around Graded Nanowire Transistor

This paper presents a self-consistent numerical model for calculating the charge profile and gate capacitance and therefore obtaining C-V characterization for a gate-all-around graded nanowire MOSFET with a high mobility axially graded In0.75Ga0.25As + In0.53Ga0.47As channel incorporating strain and atomic layer deposited Al2O3/20nm Ti gate. C-V characteristics with introduction and variation of In-composition grading and also grading in doping concentration are explored.Finite element method has been used to solve Poisson's equation and Schrödinger's equation self-consistently considering wave function penetration and other quantum effects to calculate gate capacitance and charge profile for different gate biases. The device parameters are taken from a recently introduced experimental device.

cond-mat.mtrl-sci↗