Strain-tunable magnetism and nodal loops in monolayer MnB

TL;DR

This study predicts that monolayer MnB can exhibit tunable magnetic and topological properties, including a strain-induced phase transition from antiferromagnetic to ferromagnetic states with Weyl nodal lines, offering new avenues for spintronics.

Contribution

First-principles calculations reveal strain-tunable magnetism and topological nodal loops in monolayer MnB, a novel 2D material with potential for quantum phase transition studies.

Findings

Coexistence of antiferromagnetism and Dirac nodal loops near Fermi level.

Strain induces a transition to ferromagnetic phase with Weyl nodal lines.

Magnetic critical temperatures and symmetry-protected properties analyzed.

Abstract

Designing two-dimensional (2D) materials with magnetic and topological properties has continuously attracted intense interest in fundamental science and potential applications. Here, on the basis of first-principles calculations, we predict the coexistence of antiferromagnetism and Dirac nodal loop (NL) in the monolayer MnB, where the band crossing points are very close to the Fermi Level. Remarkably, a moderate strain can induce an antiferromagnetic to ferromagnetic phase transition, driving the monolayer MnB to a ferromagnetic metal with Weyl NLs. Such a type of topological quantum phase transition has not been observed before. In addition, the symmetry-protected properties of the two types of NLs as well as the magnetic critical temperatures are investigated. The controllable magnetic and topological order in monolayer MnB offers a unique platform for exploring topological quantum phase transitions and realizing nanospintronic devices.