CoTe2: A quantum critical Dirac metal with strong spin fluctuations

TL;DR

This paper investigates orthorhombic CoTe2, revealing its proximity to ferromagnetism suppressed by spin fluctuations, and identifies it as a Dirac metal with nodal lines, combining quantum criticality and topological features.

Contribution

It demonstrates that CoTe2 is a quantum critical Dirac metal with strong spin fluctuations and topological Dirac lines, a novel combination of properties.

Findings

CoTe2 is close to ferromagnetism but remains paramagnetic due to spin fluctuations.

Identification of nodal Dirac lines in CoTe2's electronic structure.

CoTe2 exhibits properties linking quantum criticality with topological Dirac features.

Abstract

Quantum critical points separating weak ferromagnetic and paramagnetic phases trigger many novel phenomena. Dynamical spin fluctuations not only suppress the long-range order, but can also lead to unusual transport and even superconductivity. Combining quantum criticality with topological electronic properties presents a rare and unique opportunity. Here, by means of ab initio calculations and magnetic, thermal, and transport measurements, we show that the orthorhombic CoTe$_2$ is close to ferromagnetism, which appears suppressed by spin fluctuations. Calculations and transport measurements reveal nodal Dirac lines, making it a rare combination of proximity to quantum criticality and Dirac topology.