Coexistence of topological Weyl and nodal-ring states in ferromagnetic and ferrimagnetic double perovskites

TL;DR

This paper predicts that certain double perovskites are intrinsic ferromagnetic and ferrimagnetic topological materials hosting Weyl points and nodal rings, with potential applications in spintronics and quantum technologies.

Contribution

It introduces first-principles predictions of intrinsic topological states in double perovskites, expanding the range of materials for topological quantum applications.

Findings

Ba2CdReO6 is an intrinsic ferromagnetic topological semi-half-metal.

Ba2FeMoO6 is a ferrimagnetic topological half-metal.

Both materials host Weyl points and spin-polarized nodal rings near the Fermi level.

Abstract

Magnetic topological quantum materials have attracted great attention due to their exotic topological quantum physics induced by the interplay among crystalology, magnetism, and topology, which is of profound importance to fundamental research and technology applications. However, limited materials are experimentally available, most of whom are realized by magnetic impurity doping or heterostructural constructions. In this work, based on the first-principles calculations, we predict that double perovskite Ba2CdReO6 is an intrinsic ferromagnetic topological semi-half-metal, while the ferrimagnetic double perovskite with space group symmetry Fm-3m, such as Ba2FeMoO6, belongs to a topological half-metal. One pair of Weyl points and fully spin-polarized nodal-ring states are found in the vicinity of the Fermi level in Ba2CdReO6. Its two-dimensional nearly flat drumhead surface states are fully spin-polarized. In Ba2FeMoO6, however, there exist four pairs of Weyl points and two fully spin-polarized nodal-rings near the Fermi level. These topological properties are stable in the presence of spin-orbit coupling. This makes these materials be an appropriate platform for studying the emerging intriguing properties, especially for the applications in spintronics, information technology, and topological superconductivity.