Persistent exchange splitting in a chiral helimagnet Cr1/3NbS2

TL;DR

This study combines ARPES and ab-initio calculations to reveal persistent exchange splitting in Cr1/3NbS2, highlighting the role of conduction electrons and short-range magnetic order in its chiral helimagnetic state.

Contribution

It provides the first detailed investigation of the electronic structure and exchange splitting in Cr1/3NbS2, revealing persistent magnetic effects above the Curie temperature.

Findings

Exchange splitting follows magnetic moment below Tc

Persistent exchange splitting above Tc suggests short-range order

Strong hybridization between Nb- and Cr-derived states

Abstract

Using high-resolution angle-resolved photoemission spectroscopy (ARPES) and ab-initio calculation, we systematically investigate the electronic structure of the chiral helimagnet Cr1/3NbS2 and its temperature evolution. The comparison with NbS2 suggests that the electronic structure of Cr1/3NbS2 is strongly modified by the intercalation of Cr atoms. Our ab-initio calculation, consistent with experimental result, suggests strong hybridization between Nb- and Cr-derived states near the Fermi level. In the chiral helimagnetic state (below the Curie temperature Tc), we observe exchange splitting of the energy bands crossing EF, which follows the temperature evolution of the magnetic moment, suggesting an important role of the conduction electrons in the long-range magnetic ordering. Interestingly, the exchange splitting persists far above Tc with negligible temperature dependence, in drastic contrast to the itinerant ferromagnetism described by the Stoner model, indicating the existence of short-range magnetic order. Our results provide important insights into the microscopic mechanism of the chiral helimagnetic ordering in Cr1/3NbS2.