Evidence for Half-Metallicity in n-type HgCr2Se4

TL;DR

This study provides experimental evidence that n-type HgCr2Se4 exhibits half-metallicity, with high spin polarization and magnetic properties consistent with theoretical predictions of a magnetic Weyl semimetal.

Contribution

The paper demonstrates the half-metallic nature of n-HgCr2Se4 through magnetization, transport, and Andreev reflection spectroscopy, confirming theoretical predictions.

Findings

Spin polarization up to 97% in HgCr2Se4

Magnetic moments consistent with integer electron spins

Evidence supporting n-HgCr2Se4 as a half metal

Abstract

High quality HgCr$_2$Se$_4$ single crystals have been investigated by magnetization, electron transport and Andreev reflection spectroscopy. In the ferromagnetic ground state, the saturation magnetic moment of each unit cell corresponds to an integer number of electron spins (3 $\mu_B$/Cr$^{3+}$), and the Hall effect measurements suggest n-type charge carriers. Spin polarizations as high as $97\%$ were obtained from fits of the differential conductance spectra of HgCr$_2$Se$_4$/Pb junctions with the modified Blonder-Tinkham-Klapwijk (BTK) theory. The temperature and bias-voltage dependencies of the sub-gap conductance are consistent with recent theoretical calculations based on spin active scatterings at a superconductor/half metal interface. Our results suggest that n-HgCr$_2$Se$_4$ is a half metal, in agreement with theoretical calculations that also predict undoped HgCr$_2$Se$_4$ is a magnetic Weyl semimetal.