Hall detection of a ppm spin polarization

TL;DR

This paper demonstrates that a Hall effect can detect extremely small spin polarizations, even as low as one excess spin in a million, at room temperature, offering a new sensitive method for spin detection in spintronics.

Contribution

The study introduces a novel Hall effect mechanism sensitive to tiny spin polarizations, expanding detection capabilities beyond traditional methods.

Findings

Detection of one excess spin in a million at room temperature

Hall effect driven by energy derivative related to spin Nernst effect

Potential for highly sensitive spin detection in spintronics

Abstract

Hall effects have been employed as sensitive detectors of magnetic fields and magnetizations. In spintronics, exotic phenomena often emerge from a non-equilibrium spin polarization or magnetization, that is very difficult to measure directly. The challenge is due to the tiny total moment, which is out of reach of superconducting quantum interference devices and vibrating sample magnetometers or spectroscopic methods such as X-ray magnetic circular dichroism. The Kerr effect is sufficiently sensitive only in direct gap semiconductors, in which the Kerr angle can be resonantly enhanced. Here we demonstrate that even one excess spin in a million can be detected by a Hall effect at room temperature. The novel Hall effect is not governed by the spin Hall conductivity but by its energy derivative thereby related to the spin Nernst effect.