TY - JOUR

T1 - Localization of helical edge states in the absence of external magnetic field

AU - Bubis, A. V.

AU - Mikhailov, N. N.

AU - Dvoretsky, S. A.

AU - Nasibulin, A. G.

AU - Tikhonov, E. S.

N1 - Funding Information: This work was financially supported by the Russian Science Foundation Grant No. 18-72-10135 (device fabrication, all the measurements, analysis of the magnetotransport behavior of the short edges). Fabrication of the devices was performed using the equipment of MIPT Shared Facilities Center. Influence of the external magnetic field on the conductance of the long edges was analyzed under the state task of the ISSP RAS. We thank I. S. Burmistrov, Y.-Z. Chou, V. S. Khrapai, R. M. Nandkishore, and L. Radzihovsky for useful discussions. We also thank E. M. Baeva, A. K. Grebenko, G. N. Goltsman, A. I. Kardakova, and V. N. Zverev for technical assistance. Publisher Copyright: © 2021 American Physical Society.

PY - 2021/11/15

Y1 - 2021/11/15

N2 - Theoretically, the helical edge states of two-dimensional topological insulators are protected from coherent backscattering due to nonmagnetic disorder provided electron interactions are not too strong. Experimentally, the edges typically do not demonstrate systematic and robust quantization, but at the same time little is known about the sub-Kelvin temperature behavior. Here, we report the surprising localization of the edge states in an 8-nm HgTe quantum well in zero magnetic field at millikelvin temperatures. Additionally, the magnetoresistance data at 0.5K for edges a few micrometers long suggest the field-dependent localization length lB∝B-α, with α ranging approximately from 1.6 to 2.8 at fields B≲0.1T and α≈1.1 at higher fields up to 0.5T. In the frame of the disordered interacting edge, these values of α correspond to the Luttinger liquid parameters K≈0.9-1.1 and K≈0.6, respectively. We discuss possible scenarios which could result in zero magnetic field localization.

AB - Theoretically, the helical edge states of two-dimensional topological insulators are protected from coherent backscattering due to nonmagnetic disorder provided electron interactions are not too strong. Experimentally, the edges typically do not demonstrate systematic and robust quantization, but at the same time little is known about the sub-Kelvin temperature behavior. Here, we report the surprising localization of the edge states in an 8-nm HgTe quantum well in zero magnetic field at millikelvin temperatures. Additionally, the magnetoresistance data at 0.5K for edges a few micrometers long suggest the field-dependent localization length lB∝B-α, with α ranging approximately from 1.6 to 2.8 at fields B≲0.1T and α≈1.1 at higher fields up to 0.5T. In the frame of the disordered interacting edge, these values of α correspond to the Luttinger liquid parameters K≈0.9-1.1 and K≈0.6, respectively. We discuss possible scenarios which could result in zero magnetic field localization.

UR - http://www.scopus.com/inward/record.url?scp=85119099064&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.104.195405

DO - 10.1103/PhysRevB.104.195405

M3 - Article

AN - SCOPUS:85119099064

VL - 104

JO - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 19

M1 - 195405

ER -