Magnetoresistivity in a Tilted Magnetic Field in p-Si/SiGe/Si Heterostructures with an Anisotropic g-Factor: Part II

TL;DR

This study investigates the magnetoresistance behavior in p-Si/SiGe/Si heterostructures with anisotropic g-factors under tilted magnetic fields, revealing a ferromagnetic-paramagnetic transition and Landau level crossing effects.

Contribution

It provides new insights into the Landau level crossing and magnetic phase transitions in p-Si/SiGe/Si heterostructures with anisotropic g-factors under tilted magnetic fields.

Findings

Ferromagnetic-paramagnetic transition observed at specific hole density.

Landau levels crossing and divergence depend on tilt angle.

Energy gap opens at high tilt angles.

Abstract

The magnetoresistance components $\rho_{xx}$ and $\rho_{xy}$ were measured in two p-Si/SiGe/Si quantum wells that have an anisotropic g-factor in a tilted magnetic field as a function of temperature, field and tilt angle. Activation energy measurements demonstrate the existence of a ferromagnetic-paramagnetic (F-P) transition for a sample with a hole density of $p$=2$\times10^{11}$\,cm$^{-2}$. This transition is due to crossing of the 0$\uparrow$ and 1$\downarrow$ Landau levels. However, in another sample, with $p$=7.2$\times10^{10}$\,cm$^{-2}$, the 0$\uparrow$ and 1$\downarrow$ Landau levels coincide for angles $\Theta$=0-70$^{\text{o}}$. Only for $\Theta$ > 70$^{\text{o}}$ do the levels start to diverge which, in turn, results in the energy gap opening.