New highly-anisotropic Rh-based Heusler compound for magnetic recording

TL;DR

This paper introduces Rh2CoSb, a new Rh-based Heusler compound with high anisotropy and thermal conductivity, suitable for heat-assisted magnetic recording to achieve ultra-high data densities.

Contribution

The study reports the discovery and characterization of Rh2CoSb as a rare-earth free hard magnet with exceptional anisotropy and thermal properties for magnetic recording applications.

Findings

Magnetocrystalline anisotropy of 3.6 MJ/m³ at low temperature.

High thermal conductivity of 20 W/m·K.

Potential for recording densities over 10 Tb/in².

Abstract

The development of high-density magnetic recording media is limited by the superparamagnetism in very small ferromagnetic crystals. Hard magnetic materials with strong perpendicular anisotropy offer stability and high recording density. To overcome the difficulty of writing media with a large coercivity, heat assisted magnetic recording (HAMR) has been developed, rapidly heating the media to the Curie temperature Tc before writing, followed by rapid cooling. Requirements are a suitable Tc, coupled with anisotropic thermal conductivity and hard magnetic properties. Here we introduce Rh2CoSb as a new hard magnet with potential for thin film magnetic recording. A magnetocrystalline anisotropy of 3.6 MJm-3 is combined with a saturation magnetization of {\mu}0Ms = 0.52 T at 2 K (2.2 MJm-3 and 0.44 T at room-temperature). The magnetic hardness parameter of 3.7 at room temperature is the highest observed for any rare-earth free hard magnet. The anisotropy is related to an unquenched orbital moment of 0.42 {\mu}B on Co, which is hybridized with neighbouring Rh atoms with a large spin-orbit interaction. Moreover, the pronounced temperature-dependence of the anisotropy that follows from its Tc of 450 K, together with a high thermal conductivity of 20 Wm-1K-1, makes Rh2CoSb a candidate for development for heat assisted writing with a recording density in excess of 10 Tb/in2.