TY - JOUR

T1 - Sample-dependent Dirac-point gap in and its response to applied surface charge

T2 - A combined photoemission and ab initio study

AU - Shikin, A. M.

AU - Estyunin, D. A.

AU - Zaitsev, N. L.

AU - Glazkova, D.

AU - Klimovskikh, I. I.

AU - Filnov, S. O.

AU - Rybkin, A. G.

AU - Schwier, E. F.

AU - Kumar, S.

AU - Kimura, A.

AU - Mamedov, N.

AU - Aliev, Z.

AU - Babanly, M. B.

AU - Kokh, K.

AU - Tereshchenko, O. E.

AU - Otrokov, M. M.

AU - Chulkov, E. V.

AU - Zvezdin, K. A.

AU - Zvezdin, A. K.

N1 - Funding Information: The authors acknowledge support by the Saint Petersburg State University Grant No. ID 73028629, Russian Science Foundation Grant No. 18-12-00062 in part of the photoemission measurements and total analysis of the results, Grant No. 18-12-00169-p in part of the electronic band structure calculations and Grant No. 20-42-08002 in part of analysis of magnetic properties and Science Development Foundation under the President of the Republic of Azerbaijan Grant No. EI F-BGM-4-RFTF1/2017-21/04/1-M-02. M.M.O. acknowledges the support by Spanish Ministerio de Ciencia e Innovación (Grant No. PID2019-103910GB-I00). K.K. and O.E.T. acknowledge the support from state assignment of IGM SB RAS and ISP SB RAS. Publisher Copyright: © 2021 American Physical Society

PY - 2021/9/15

Y1 - 2021/9/15

N2 - Recently discovered intrinsic antiferromagnetic topological insulator presents an exciting platform for realization of the quantum anomalous Hall effect and a number of related phenomena at elevated temperatures. An important characteristic making this material attractive for applications is its predicted large magnetic gap at the Dirac point (DP). However, while the early experimental measurements reported on large DP gaps, a number of recent studies claimed to observe a gapless dispersion of the Dirac cone. Here, using micro()-laser angle-resolved photoemission spectroscopy, we study the electronic structure of 15 different samples, grown by two different chemists groups. Based on the careful energy distribution curves analysis, the DP gaps between 15 and 65 meV are observed, as measured below the Néel temperature at about 10-16 K. At that, roughly half of the studied samples show the DP gap of about 30 meV, while for a quarter of the samples the gaps are in the 50 to 60 meV range. Summarizing the results of both our and other groups, in the currently available samples the DP gap can acquire an arbitrary value between a few and several tens of meV. Furthermore, based on the density functional theory, we discuss a possible factor that might contribute to the reduction of the DP gap size, which is the excess surface charge that can appear due to various defects in surface region. We demonstrate that the DP gap is influenced by the applied surface charge and even can be closed, which can be taken advantage of to tune the DP gap size.

AB - Recently discovered intrinsic antiferromagnetic topological insulator presents an exciting platform for realization of the quantum anomalous Hall effect and a number of related phenomena at elevated temperatures. An important characteristic making this material attractive for applications is its predicted large magnetic gap at the Dirac point (DP). However, while the early experimental measurements reported on large DP gaps, a number of recent studies claimed to observe a gapless dispersion of the Dirac cone. Here, using micro()-laser angle-resolved photoemission spectroscopy, we study the electronic structure of 15 different samples, grown by two different chemists groups. Based on the careful energy distribution curves analysis, the DP gaps between 15 and 65 meV are observed, as measured below the Néel temperature at about 10-16 K. At that, roughly half of the studied samples show the DP gap of about 30 meV, while for a quarter of the samples the gaps are in the 50 to 60 meV range. Summarizing the results of both our and other groups, in the currently available samples the DP gap can acquire an arbitrary value between a few and several tens of meV. Furthermore, based on the density functional theory, we discuss a possible factor that might contribute to the reduction of the DP gap size, which is the excess surface charge that can appear due to various defects in surface region. We demonstrate that the DP gap is influenced by the applied surface charge and even can be closed, which can be taken advantage of to tune the DP gap size.

UR - http://www.scopus.com/inward/record.url?scp=85116321146&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.104.115168

DO - 10.1103/PhysRevB.104.115168

M3 - Article

AN - SCOPUS:85116321146

VL - 104

JO - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 11

M1 - 115168

ER -