Anisotropic magnetism and band evolution induced by ferromagnetic phase transition in titanium-based kagome ferromagnet SmTi3Bi4

TL;DR

This study reports on the anisotropic magnetism and band structure evolution in the newly discovered titanium-based kagome ferromagnet SmTi3Bi4, highlighting its ferromagnetic transition, electronic features, and potential for topological applications.

Contribution

The paper reveals the ferromagnetic phase transition and associated band evolution in SmTi3Bi4, a titanium-based kagome magnet, combining experimental and theoretical insights.

Findings

Ferromagnetic transition at 23.2 K with large magnetic anisotropy.

Observation of Dirac point and van Hove singularities in the electronic structure.

Band splitting and gap closing linked to ferromagnetic order and exchange coupling.

Abstract

Kagome magnets with diverse topological quantum responses are crucial for next-generation topological engineering. The anisotropic magnetism and band evolution induced by ferromagnetic phase transition (FMPT) is reported in a newly discovered titanium-based kagome ferromagnet S mTi3 Bi4, which features a distorted Ti kagome lattice and S m atomic zig-zag chains. Temperature-dependent resistivity, heat capacity, and magnetic susceptibility reveal a ferromagnetic ordering temperature Tc of 23.2 K. A large magnetic anisotropy, observed by applying the magnetic field along three crystallographic axes, identifies the b axis as the easy axis. Angle-resolved photoemission spectroscopy with first-principles calculations unveils the characteristic kagome motif, including the Dirac point at the Fermi level and multiple van Hove singularities. Notably, a band splitting and gap closing attributed to FMPT is observed, originating from the exchange coupling between S m 4 f local moments and itinerant electrons of the kagome Ti atoms, as well as the time-reversal symmetry breaking induced by the long-range ferromagnetic order. Considering the large in-plane magnetization and the evolution of electronic structure under the influence of ferromagnetic ordering, such materials promise to be a new platform for exploring the intricate electronic properties and magnetic phases based on the kagome lattice.