TY - JOUR

T1 - Features and applications of the energy shift of the topological surface state

AU - Estyunin, D. A.

AU - Schwier, E. F.

AU - Kumar, S.

AU - Shimada, K.

AU - Kokh, K.

AU - Tereshchenko, O. E.

AU - Shikin, A. M.

N1 - Funding Information: The authors acknowledge support from Ministry of Science and Higher Education of the Russian Federation Grant No. 075-15-2020-797 (13.1902.21.0024). ARPES measurements were performed under Proposals No. 19AG048 and No. 19AG049. We thank N-BARD, Hiroshima University, for supplying liquid He. Publisher Copyright: © 2022 American Physical Society.

PY - 2022/3/15

Y1 - 2022/3/15

N2 - Contemporary studies of magnetic topological insulators (TIs) aimed at investigating Dirac point (DP) gaps by angle-resolved photoemission spectroscopy (ARPES) require ultrahigh energy, momentum, and spatial resolution. Despite satisfying all these conditions, accurate measurements can be spoiled by the well-known, but often neglected, effect of the energy shift of bands, in particular the topological surface state (TSS), due to sample contamination and irradiation. Thus, in this work we focus on the effect of TI irradiation with laser light (h?=6.3 eV) on the measurability of its electronic structure using the ARPES method. We find that the distribution of the shifted TSS is sufficiently localized and remains stable over time under constant conditions. Therefore, it can be used to store information. The TSS retains its spin pattern regardless of irradiation, as demonstrated by dichroic ARPES measurements. However, irradiation leads to a significant broadening of the TSS, accompanied by a drop in its intensity. All these factors complicate the analysis of the states near the DP and the DP gap size. Finally, using a simple model, we demonstrate the variability of the DP gap over time in the resulting ARPES image, caused by both shift and broadening effects. Thus, accurate values of the DP gap can be obtained by measuring over a relatively small period of time, which is determined by a certain time constant of the energy shift.

AB - Contemporary studies of magnetic topological insulators (TIs) aimed at investigating Dirac point (DP) gaps by angle-resolved photoemission spectroscopy (ARPES) require ultrahigh energy, momentum, and spatial resolution. Despite satisfying all these conditions, accurate measurements can be spoiled by the well-known, but often neglected, effect of the energy shift of bands, in particular the topological surface state (TSS), due to sample contamination and irradiation. Thus, in this work we focus on the effect of TI irradiation with laser light (h?=6.3 eV) on the measurability of its electronic structure using the ARPES method. We find that the distribution of the shifted TSS is sufficiently localized and remains stable over time under constant conditions. Therefore, it can be used to store information. The TSS retains its spin pattern regardless of irradiation, as demonstrated by dichroic ARPES measurements. However, irradiation leads to a significant broadening of the TSS, accompanied by a drop in its intensity. All these factors complicate the analysis of the states near the DP and the DP gap size. Finally, using a simple model, we demonstrate the variability of the DP gap over time in the resulting ARPES image, caused by both shift and broadening effects. Thus, accurate values of the DP gap can be obtained by measuring over a relatively small period of time, which is determined by a certain time constant of the energy shift.

UR - http://www.scopus.com/inward/record.url?scp=85126976501&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.105.125303

DO - 10.1103/PhysRevB.105.125303

M3 - Article

AN - SCOPUS:85126976501

VL - 105

JO - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 12

M1 - 125303

ER -