Detection of Magnetic Gap in Topological Surface States of MnBi$_{2}$Te$_{4}$
Hao-Ran Ji1†, Yan-Zhao Liu1†, He Wang2, Jia-Wei Luo1, Jia-Heng Li3,4, Hao Li5,6, Yang Wu6,7, Yong Xu3,4,8, and Jian Wang1,3,9,10*
1International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China 2Department of Physics, Capital Normal University, Beijing 100048, China 3State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China 4Frontier Science Center for Quantum Information, Beijing 100084, China 5School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China 6Tsinghua-Foxconn Nanotechnology Research Center and Department of Physics, Tsinghua University, Beijing 100084, China 7Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China 8RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan 9CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China 10Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Abstract：Recently, intrinsic antiferromagnetic topological insulator MnBi$_{2}$Te$_{4}$ 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 MnBi$_{2}$Te$_{4}$. 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 MnBi$_{2}$Te$_{4}$ is revealed.
. [J]. 中国物理快报, 2021, 38(10): 107404-.
Hao-Ran Ji, Yan-Zhao Liu, He Wang, Jia-Wei Luo, Jia-Heng Li, Hao Li, Yang Wu, Yong Xu, and Jian Wang. Detection of Magnetic Gap in Topological Surface States of MnBi$_{2}$Te$_{4}$. Chin. Phys. Lett., 2021, 38(10): 107404-.
Katmis F, Lauter V, Nogueira F S, Assaf B A, Jamer M E, Wei P, Satpati B, Freeland J W, Eremin I, Heiman D, Jarillo-Herrero P, and Moodera J S 2016 Nature533 513
[7]
Mogi M, Kawamura M, Yoshimi R, Tsukazaki A, Kozuka Y, Shirakawa N, Takahashi K S, Kawasaki M, and Tokura Y 2017 Nat. Mater.16 516
Chang C Z, Zhang J S, Feng X, Shen J, Zhang Z C, GuO M H, Li K, Ou Y B, Wei P, Wang L L, Ji Z Q, Feng Y, Ji S H, Chen X, Jia J F, Dai X, Fang Z, Zhang S C, He K, Wang Y Y, Lu L, Ma X C, and Xue Q K 2013 Science340 167
[10]
Otrokov M M, Klimovskikh I I, Bentmann H, Estyunin D, Zeugner A, Aliev Z S, Wolter S G A U B, Koroleva A V, Shikin A M, Blanco-Rey M, Hoffmann M, Rusinov I P, Vyazovskaya A Y, Eremeev S V, Koroteev Y M, Kuznetsov V M, Freyse F, Sánchez-Barriga J, Amiraslanov I R, Babanly M B, Mamedov N T, Abdullayev N A, Zverev V N, Alfonsov A, Kataev V, Büchner B, Schwier E F, Kumar S, Kimura A, Petaccia L, Di Santo G, Vidal R C, Schatz S, Kißner K, Ünzelmann M, Min C H, Moser S, Peixoto T R F, Reinert F, Ernst A, Echenique P M, Isaeva A, and Chulkov E V 2019 Nature576 416
[11]
Yan J Q, Zhang Q, Heitmann T, Huang Z, Chen K Y, Cheng J G, Wu W, Vaknin D, Sales B C, and McQueeney R J 2019 Phys. Rev. Mater.3 064202
Hao Y J, Liu P F, Feng Y, Ma X M, Schwier E F, Arita M, Kumar S, Hu C W, Lu R E, Zeng M, Wang Y, Hao Z Y, Sun H Y, Zhang K, Mei J W, Ni N, Wu L S, Shimada K, Chen C Y, Liu Q H, and Liu C 2019 Phys. Rev. X9 041038
[19]
Li H, Gao S Y, Duan S F, Xu Y F, Zhu K J, Tian S J, Gao J C, Fan W H, Rao Z C, Huang J R, Li J J, Yan D Y, Liu Z T, Liu W L, Huang Y B, Li Y L, Liu Y, Zhang G B, Zhang P, Kondo T, Shin S, Lei H C, Shi Y G, Zhang W T, Weng H M, Qian T, and Ding H 2019 Phys. Rev. X9 041039
[20]
Chen Y J, Xu L X, Li J H, Li Y W, Wang H Y, Zhang C F, Li H, Wu Y, Liang A J, Chen C, Jung S W, Cacho C, Mao Y H, Liu S, Wang M X, Guo Y F, Xu Y, Liu Z K, Yang L X, and Chen Y L 2019 Phys. Rev. X9 041040
Soulen Jr R J, Byers J M, Osofsky M S, Nadgorny B, Ambrose T, Cheng S F, Broussard P R, Tanaka C T, Nowak J, Moodera J S, Barry A, and Coey J M D 1998 Science282 85
[28]
Tang C, Chang C Z, Zhao G J, Liu Y W, Jiang Z L, Liu C X, McCartney M R, Smith D J, Chen T Y, Moodera J S, and Shi J 2017 Sci. Adv.3 e1700307
[29]
Gong Y, Guo J W, Li J H, Zhu K J, Liao M H, Liu X Z, Zhang Q H, Gu L, Tang L, Feng X, Zhang D, Li W, Song C L, Wang L L, Yu P, Chen X, Wang Y Y, Yao H, Duan W H, Xu Y, Zhang S C, Ma X C, Xue Q K, and He K 2019 Chin. Phys. Lett.36 076801
2021, Vol. 38 
