Influence of spin polarization on resistivity of a two-dimensional electron gas in Si MOSFET at metallic densities

TL;DR

This study investigates how spin polarization influences resistivity in a high-density two-dimensional electron gas in silicon MOSFETs, revealing a universal scaling behavior of positive magnetoresistance with magnetic field and spin polarization.

Contribution

It demonstrates that the positive magnetoresistance curves scale with the ratio B/B_c, incorporating temperature effects and the transition to quasi-3D transport regimes, extending understanding to metallic densities.

Findings

PMR curves merge when scaled by B/B_c across high densities.

Temperature dependence of B_c is crucial for curve merging at densities near n_c.

Transition from 2D to quasi-3D transport affects PMR at strong magnetic fields.

Abstract

Positive magnetoresistance (PMR) of a silicon MOSFET in parallel magnetic fields B has been measured at high electron densities n >> n_c where n_c is the critical density of the metal-insulator transition (MIT). It turns out that the normalized PMR curves, R(B)/R(0), merge together when the field is scaled according to B/B_c(n) where B_c is the field in which electrons become fully spin polarized. The values of B_c have been calculated from the simple equality between the Zeeman splitting energy and the Fermi energy taking into account the experimentally measured dependence of the spin susceptibility on the electron density. This extends the range of validity of the scaling all the way to a deeply metallic regime far away from MIT. The subsequent analysis of PMR for low n >~ n_c demonstrated that the merging of the initial parts of curves can bee achieved only with taking into account the temperature dependence of B_c. It is also shown that the shape of the PMR curves at strong magnetic fields is affected by a crossover from a purely two-dimensional (2D) electron transport to a regime where out-of-plane carrier motion becomes important (quasi-three-dimensional regime).