Electronic topological transition and non-collinear magnetism in compressed hcp Co

TL;DR

This paper investigates how electronic topological transitions in compressed hcp Co influence its elastic and magnetic properties, revealing a transition to a non-collinear magnetic state at high pressures.

Contribution

It uncovers the sequence of electronic topological transitions in hcp Co and links them to the stabilization of a non-collinear magnetic state under high pressure.

Findings

Electronic topological transitions affect Co's properties.

Non-collinear magnetism stabilizes at high pressure.

Transition from ferromagnetic to non-magnetic phase predicted.

Abstract

Recent experiments showed that Co undergoes a phase transition from ferromagnetic hcp phase to non-magnetic fcc one around 100 GPa. Since the transition is of first order, a certain region of co-existence of the two phases is present. By means of \textit{ab initio} calculations, we found that the hcp phase itself undergoes a series of electronic topological transitions (ETTs), which affects both elastic and magnetic properties of the material. Most importantly, we propose that the sequence of ETTs lead to the stabilisation of a non-collinear spin arrangement in highly compressed hcp Co. Details of this non-collinear magnetic state and the interatomic exchange parameters that are connected to it, are presented here.