High-temperature ideal Weyl semimetal phase and Chern insulator phase in ferromagnetic BaEuNiOsO6 and its (111) (BaEuNiOsO6)/(BaTiO3)10 superlattice
Journal
Physical Review B
Journal Volume
104
Journal Issue
18
Date Issued
2021
Author(s)
Lu H.-S
Abstract
Weyl semimetals (WSMs) have recently stimulated intensive interest because they exhibit fascinating physical properties and also promise exciting technological applications. So far, however, the few confirmed magnetic WSMs generally have a large number of Weyl points either located away from the Fermi level (EF) or shrouded by nontopological Fermi surface pockets. Based on first-principles density functional theory calculations, we establish cubic double perovskite BaEuNiOsO6 to be a high Curie temperature (Tc) ferromagnetic (FM) WSM with magnetization along the [111] direction, just two pairs of Weyl points at the EF and Tc=325 K. The strong FM is attributed to the strong FM Ni 3d-Eu 4f-Os 5d coupling induced by the substitution of half of Ba atoms with Eu atoms in double perovskite Ba2NiOsO6. Moreover, the momentum separation of one Weyl point pair is large, thus giving rise to not only a long (001) surface Fermi arc but also large anomalous Hall conductivity. Intriguingly, as a unique physical result of bulk BaEuNiOsO6 being a FM WSM, the (111) BaEuNiOsO6 monolayer (ML) superlattice (BaEuNiOsO6)/(BaTiO3)10 is found to be a high-temperature (Tc=210 K) Chern insulator with a large band gap of ?90 meV. Therefore, cubic double perovskite BaEuNiOsO6 will provide a superior high-temperature material platform for exploring fundamental physics of Weyl fermions, and its (111) ML superlattices will offer a high-temperature magnetic topological insulator for studying exotic quantum phenomena such as the quantum anomalous Hall effect. ? 2021 American Physical Society.
Subjects
Barium titanate; Calculations; Density functional theory; Ferromagnetic materials; Ferromagnetism; Frequency modulation; Nickel compounds; Perovskite; Density-functional theory calculations; Double perovskites; Fermi arcs; First-principle density-functional theories; Hall conductivity; High Curie temperature; Highest temperature; Insulator phasis; Large band; Technological applications; Energy gap
Type
journal article