XFe4Ge2 (X = Y, Lu) and Mn3Pt: Filling-enforced magnetic topological metals

TL;DR

This study identifies filling-enforced magnetic topological metals, specifically XFe4Ge2 (X=Y, Lu) and Mn3Pt, revealing Dirac and Weyl points protected by symmetries, with properties robust against Coulomb interactions.

Contribution

It provides a comprehensive first-principles analysis showing these materials are filling-enforced magnetic topological metals with symmetry-protected Dirac and Weyl points.

Findings

XFe4Ge2 hosts Dirac points near Fermi level protected by PT and screw symmetries.

Breaking PT symmetry splits Dirac points into Weyl nodes.

Topological properties are insensitive to Coulomb U effects.

Abstract

Magnetism, coupled with nontrivial band topology, can bring about many interesting and exotic phenomena, so that magnetic topological materials have attracted persistent research interest. However, compared with non-magnetic topological materials (TMs), the magnetic TMs are less studied, since their magnetic structures and topological phase transitions are usually complex and the first-principles predictions are usually sensitive on the effect of Coulomb interaction. In this work, we present a comprehensive investigation of XFe4Ge2 (X = Y, Lu) and Mn3Pt, and find these materials to be filling-enforced magnetic topological metals. Our first-principles calculations show that XFe4Ge2 (X = Y, Lu) host Dirac points near the Fermi level at high symmetry point S. These Dirac points are protected by PT symmetry (P and T are inversion and time-reversal transformations, respectively) and a 2-fold screw rotation symmetry. Moreover, through breaking PT symmetry, the Dirac points would split into Weyl nodes. Mn3Pt is found to host 4-fold degenerate band crossings in the whole high symmetry path of A-Z. We also utilize the GGA+U scheme to take into account the effect of Coulomb repulsion and find that the filling-enforced topological properties are naturally insensitive on U.