Spontaneous Ferromagnetism Induced Topological Transition in EuB6

The interplay between various symmetries and electronic bands topology is one of the core issues for topological quantum materials. Spontaneous magnetism, which leads to the breaking of time-reversal symmetry, has been proven to be a powerful approach to trigger various exotic topological phases. In this Letter, utilizing the combination of angle-resolved photoemission spectroscopy, magneto-optical Kerr effect microscopy, and first-principles calculations, we present the direct evidence on the realization of the long-sought spontaneous ferromagnetism induced topological transition in soft ferromagnetic EuB6. Explicitly, we reveal the topological transition is from Z2 = 1 topological insulator in paramagnetic state to chi = 1 magnetic topological semimetal in low temperature ferromagnetic state. Our results demonstrate that the simple band structure near the Fermi level and rich topological phases make EuB6 an ideal platform to study the topological phase physics.

Automated summary

This letter provides direct evidence of the spontaneous ferromagnetism induced topological transition in soft ferromagnetic EuB6, and reveals the topological transition from paramagnetic state to ferromagnetic state.