Evolution of Dopant-Concentration-Induced Magnetic Exchange Interaction in Topological Insulator Thin Films
Autor: | Fei Wang, Yi-Fan Zhao, Zi-Jie Yan, Deyi Zhuo, Hemian Yi, Wei Yuan, Lingjie Zhou, Weiwei Zhao, Moses H. W. Chan, Cui-Zu Chang |
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Rok vydání: | 2023 |
Předmět: |
Condensed Matter::Materials Science
Condensed Matter - Materials Science Condensed Matter - Mesoscale and Nanoscale Physics Condensed Matter::Superconductivity Mechanical Engineering Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences Condensed Matter::Strongly Correlated Electrons General Materials Science Bioengineering General Chemistry Condensed Matter Physics |
Zdroj: | Nano Letters. 23:2483-2489 |
ISSN: | 1530-6992 1530-6984 |
DOI: | 10.1021/acs.nanolett.2c03827 |
Popis: | Two essential ingredients for the quantum anomalous Hall (QAH) effect, i.e. topological and magnetic orders, can be combined by doping magnetic ions into a topological insulator (TI) film. Through this approach, the QAH effect has been realized in chromium (Cr)- and/or vanadium (V)-doped TI (Bi,Sb)2Te3 thin films. In this work, we synthesize both V- and Cr-doped Bi2Te3 thin films with controlled dopant concentration using molecular beam epitaxy (MBE). By performing magneto-transport measurements, we find that both systems show an unusual but yet similar ferromagnetic response with respect to magnetic dopant concentration, specifically the Curie temperature does not increase monotonically but shows a local maximum at a critical dopant concentration. Our angle-resolved photoemission spectroscopy (ARPES) measurements show that the Cr/V doping introduces hole carriers into Bi2Te3, which consequently move the chemical potential toward the charge neutral point. In addition, the Cr/V doping also reduces the spin-orbit coupling of Bi2Te3 which drives it from a nontrivial TI to a trivial semiconductor. The unusual ferromagnetic response observed in Cr/V-doped Bi2Te3 thin films is attributed to the dopant-concentration-induced magnetic exchange interaction, which displays the evolution from the van Vleck-type ferromagnetism in a nontrivial magnetic TI to the Ruderman-Kittel-Kasuya-Yosida (RKKY)-type ferromagnetism in a trivial diluted magnetic semiconductor. Our work provides insights into the ferromagnetic properties of magnetically doped TI thin films and facilitates the pursuit of high-temperature QAH effect. 17 pages, 4 figures. Comments are welcome |
Databáze: | OpenAIRE |
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