Dirac fermions in the altermagnet Ce4Sb3

TL;DR

This paper predicts that the altermagnet Ce4Sb3 hosts Dirac fermions and explores how magnetic field-induced phase transitions affect its topological electronic structure, revealing potential for novel spintronic effects.

Contribution

It is the first to demonstrate the presence of Dirac fermions in Ce4Sb3 and analyze their behavior under magnetic transitions using first-principles and tight-binding models.

Findings

Dirac fermions are present in Ce4Sb3.

Magnetic field induces transition from Dirac to sextuple degenerate points.

Spin-orbit coupling has minimal effect on Dirac fermions.

Abstract

Altermagnetism exhibits zero net magnetization and spin-splitting electronic structure. The interplay between altermagnetism and topological physics becomes an important topic in the condensed matter physics. In this letter, we propose that the altermagnet Ce4Sb3 hosts Dirac fermions through first-principles calculations and tight-binding model analysis. When subjected to external magnetic field, the altermagnet Ce4Sb3 change from altermagnetic state to ferromagnetic state. Accompanied with magnetic order transition, the four-fold degenerate Dirac points are transited into sextuple degenerate points. Especially, spin-orbital coupling effect has little influence about the Dirac fermions. The topological phases in the altermagnetic state may hold the exotic spin-splitter torque and remarkable nonlinear transport effect. Our work paves the way for exploring the interplay between altermagnetism and non-trivial topological phase.