Dirac semimetal in type IV magnetic space group

TL;DR

This paper introduces a new class of Dirac semimetals in magnetic space groups, specifically type IV, protected by antiunitary symmetries, and proposes EuCd2As2 as a candidate material for experimental study.

Contribution

It generalizes Dirac semimetals to magnetic space groups and identifies a new category in type IV MSGs, expanding the theoretical framework and potential material realizations.

Findings

Proposes EuCd2As2 as a candidate Dirac semimetal with one pair of Dirac points.

Defines a new category of Dirac semimetals in type IV magnetic space groups.

Explores topological states derived from AFM Dirac semimetals.

Abstract

Analogues of the elementary particles, Dirac fermions in condensed matter have received extensive attention for both scientific interest and device applications. In this work, we generalize the concept of Dirac semimetal (DSM) to the magnetic space groups (MSGs), and define a new category of DSM in type IV MSGs, which is protected by the antiunitarity of the product of the inversion symmetry and the nonsymmophic time-reversal symmetry. Moreover, we propose the interlayer antiferromagnetic (AFM) EuCd2As2 as a promising candidate with only one pair of Dirac points at the Fermi level. Many exotic topological states, such as the triple point semimetal and the AFM topological insulator holding of the half-quantum Hall effect, can be derived from such AFM DSMs by breaking certain symmetry, providing an ideal platform to study topological phase transitions. Our results extend the range of DSM, and open a new way to study the interplay between the DSM and other exotic topological states.