Nonlinear 2D Spin Susceptibility in a Finite Magnetic Field: Spin-Polarization Dependence

TL;DR

This paper demonstrates that the common experimental method of measuring 2D spin susceptibility via linear extrapolation from finite magnetic fields is theoretically invalid due to nonlinear magnetic field dependence, challenging previous interpretations.

Contribution

It provides a theoretical analysis showing the nonlinear magnetic field dependence of 2D spin susceptibility, invalidating standard experimental extrapolation methods.

Findings

Linear extrapolation to zero field is unjustified for 2D spin susceptibility.

Prevailing interpretations of susceptibility measurements are likely incorrect.

Interacting susceptibility cannot be reliably obtained from critical magnetic field data.

Abstract

By theoretically calculating the interacting spin susceptibility of a two-dimensional electron system in the presence of finite spin polarization, we show that the extensively employed technique of measuring the 2D spin susceptibility by linear extrapolation to a zero field from the finite-field experimental data is theoretically unjustified due to the strong nonlinear magnetic field dependence of the interacting susceptibility. Our work compellingly establishes that much of the prevailing interpretation of the 2D susceptibility measurements is incorrect, and, in general, the 2D interacting susceptibility cannot be extracted from the critical magnetic field for full spin polarization, as is routinely done experimentally.