Intrinsic magnetism in semiconducting bulk amorphous tellurium

Abstract

Magnetic semiconductors, which combine the properties of ferromagnets and semiconductors, are highly sought after for innovating information technology applications. However, only a few material families have been reported as magnetic semiconductors. In this study, we introduce pure amorphous tellurium (a-Te) as a novel candidate for magnetic semiconductors, based on a working principle distinct from most magnetic semiconductors that rely on extrinsic doping. While crystalline Te is non-magnetic, our density functional theory (DFT) calculations identify a spin-polarized gap state in a-Te above the valence band, leading to magnetization. This semiconducting magnetic state arises from a largely distorted Te site, due to Te structural units violating the octet rule, facilitated by substantially large Te 5p shells. Structural analysis with Born effective charge calculations reveals partial bond breakage and substantial charge transfer at the magnetic Te site. The structural distortions in a-Te enable local arrangement for magnetization, reminiscent of ferromagnetic carbon materials. Our findings offer insights into intrinsic magnetism and suggest a potential to increase the density of magnetic sites with simple Te material, which has demonstrated excellent thin-film transistor performance.