Detection of magnetic gap in the topological surface states of MnBi2Te4

Abstract

Recently, intrinsic antiferromagnetic topological insulator MnBi2Te4 has drawn intense research interest and leads to plenty of significant progress in physics and materials science by hosting quantum anomalous Hall effect, axion insulator state, and other quantum phases. An essential ingredient to realize these quantum states is the magnetic gap in the topological surface states induced by the out-of-plane ferromagnetism on the surface of MnBi2Te4. However, the experimental observations of the surface gap remain controversial. Here, we report the observation of the surface gap via the point contact tunneling spectroscopy. In agreement with theoretical calculations, the gap size is around 50 meV, which vanishes as the sample becomes paramagnetic with increasing temperature. The magnetoresistance hysteresis is detected through the point contact junction on the sample surface with an out-of-plane magnetic field, substantiating the surface ferromagnetism. Furthermore, the non-zero transport spin polarization coming from the ferromagnetism is determined by the point contact Andreev reflection spectroscopy. Combining these results, the magnetism-induced gap in topological surface states of MnBi2Te4 is revealed.

References in corpus (6)

• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Antiferromagnetic topological insulators
• Crystal growth and magnetic structure of MnBi2Te4
• The role of critical current on point contact Andreev Reflection spectrum between a normal metal and a superconductor
• Above 400 K Robust Perpendicular Ferromagnetic Phase in a Topological Insulator
• Mesoscopic superconductivity and high spin polarization coexisting at metallic point contacts on the Weyl semimetal TaAs

Cited by in corpus (10)

• Distinct magnetic gaps between antiferromagnetic and ferromagnetic orders driven by surface defects in the topological magnet MnBi2Te4
• Dissipationless Layertronics in Axion Insulator $\mathrm{MnB}{\mathrm{i}}_2\mathrm{T}{\mathrm{e}}_4$
• Large Exchange Bias Effect and Coverage-Dependent Interfacial Coupling in CrI3/MnBi2Te4 van der Waals Heterostructures
• Large Itinerant Electron Exchange Coupling in the Magnetic Topological Insulator MnBi2Te4
• On the topological surface states of the intrinsic magnetic topological insulator Mn-Bi-Te family
• Three-Dirac-fermion approach to unexpected universal gapless surface states of van der Waals magnetic topological insulators
• Facet dependent surface energy gap on magnetic topological insulators
• Pressure-tunable magnetic topological phases in magnetic topological insulator MnSb4Te7
• The electronic structure of intrinsic magnetic topological insulator MnBi2Te4 quantum wires
• Defect-induced displacement of topological surface state in quantum magnet MnBi${}_2$Te${}_4$