Time-reversal symmetry breaking driven topological phase transition in EuB${}_6$

Abstract

The interplay between time-reversal symmetry (TRS) and band topology plays a crucial role in topological states of quantum matter. In time-reversal-invariant (TRI) systems, the inversion of spin-degenerate bands with opposite parity leads to nontrivial topological states, such as topological insulators and Dirac semimetals. When the TRS is broken, the exchange field induces spin splitting of the bands. The inversion of a pair of spin-splitting subbands can generate more exotic topological states, such as quantum anomalous Hall insulators and magnetic Weyl semimetals. So far, such topological phase transitions driven by the TRS breaking have not been visualized. In this work, using angle-resolved photoemission spectroscopy, we have demonstrated that the TRS breaking induces a band inversion of a pair of spin-splitting subbands at the TRI points of Brillouin zone in EuB${}_6$, when a long-range ferromagnetic order is developed. The dramatic changes in the electronic structure result in a topological phase transition from a TRI ordinary insulator state to a TRS-broken topological semimetal (TSM) state. Remarkably, the magnetic TSM state has an ideal electronic structure, in which the band crossings are located at the Fermi level without any interference from other bands. Our findings not only reveal the topological phase transition driven by the TRS breaking, but also provide an excellent platform to explore novel physical behavior in the magnetic topological states of quantum matter.

arXiv comment22 pages, 7 figures, accepted by Phys. Rev. X

References in corpus (29)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• $Z_2$ Topological Order and the Quantum Spin Hall Effect
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Topological Insulators with Inversion Symmetry
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Quantum Spin Hall Effect
• Magnetic-field-induced quantized anomalous Hall effect in intrinsic magnetic topological insulator MnBi${}_2$Te${}_4$
• Giant anomalous Hall effect in a ferromagnetic Kagome-lattice semimetal
• Intrinsic magnetic topological insulators in van der Waals layered MnBi${}_2$Te${}_4$-family materials
• High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator
• Magnetic Weyl Semimetal Phase in a Kagome Crystal
• Robust axion insulator and Chern insulator phases in a two-dimensional antiferromagnetic topological insulator
• Trajectory of Anomalous Hall Effect toward the Quantized State in a Ferromagnetic Topological Insulator
• Large intrinsic anomalous Hall effect in half-metallic ferromagnet Co3Sn2S2 with magnetic Weyl fermions
• Scale-Invariant Dissipationless Chiral Transport in Magnetic Topological Insulators beyond the Two-Dimensional Limit
• Discovery of topological Weyl fermion lines and drumhead surface states in a room temperature magnet
• High-Chern-Number and High-Temperature Quantum Hall Effect without Landau Levels
• Quantum anomalous Hall effect in magnetic topological insulators
• Bulk Band Gaps in Divalent Hexaborides
• Magnetic semimetals and quantized anomalous Hall effect in EuB6
• Emerging chiral edge states from the confinement of a magnetic Weyl semimetal in Co${}_3$Sn${}_2$S${}_2$
• Magnetic Polarons and the Metal-Semiconductor Transition in (Eu,La)B6 and EuO: Raman Scattering Studies
• Kondo and anti-Kondo coupling to local moments in EuB${}_6$
• Nonlinear Hall effect as a signature of electronic phase separation in the semimetallic ferromagnet EuB6
• Magnetic phase separation in EuB6 detected by muon spin rotation
• Electronic properties of EuB6 in the ferromagnetic regime: Half-metal versus semiconductor
• Comparative Scanning Tunneling Microscopy Study on Hexaborides

Cited by in corpus (10)

• Electronic structure and topology across $T_c$ in magnetic Weyl semimetal Co${}_3$Sn${}_2$S${}_2$
• Magnetic-field modulation of topological electronic states and emergent magneto-transport in a magnetic Weyl semimetal
• Large magnetoresistance and first-order phase transition in antiferromagnetic single-crystalline EuAg${}_4$Sb${}_2$
• Possible quantum nematic in a colossal magnetoresistance material
• Axion insulator, Weyl points, quantum anomalous Hall effect and magnetic topological phase transition in Eu3In2As4
• Unveiling Symmetry Instability induced by Topological Phase Transitions
• Sensing Out-of-Equilibrium and Quantum Non-Gaussian environments via induced Time-Reversal Symmetry Breaking on the quantum-probe dynamics
• A new ferromagnetic semiconductor system of Eu${}_{1-x}$Sr${}_x$AgP $(x=0.0-0.6)$ compounds: Crystallographic, magnetic, and magneto-resistive properties
• Magnetic domain structure and domain wall bound states of topological semimetal EuB6
• Magnetic topological Weyl fermions in half-metallic In${}_2$CoSe${}_4$