Evolution of Dopant-Concentration-Induced Magnetic Exchange Interaction in Topological Insulator Thin Films.
basic_science · Level V
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- Record sourced from PubMed, PMID 36930727.
- Also identified by DOI 10.1021/acs.nanolett.2c03827.
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Abstract
To date, the quantum anomalous Hall effect has been realized in chromium (Cr)- and/or vanadium(V)-doped topological insulator (Bi,Sb)<sub>2</sub>Te<sub>3</sub> thin films. In this work, we use molecular beam epitaxy to synthesize both V- and Cr-doped Bi<sub>2</sub>Te<sub>3</sub> thin films with controlled dopant concentration. By performing magneto-transport measurements, we find that both systems show an unusual 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. We attribute this unusual ferromagnetic response observed in Cr/V-doped Bi<sub>2</sub>Te<sub>3</sub> thin films to the dopant-concentration-induced magnetic exchange interaction, which displays evolution from van Vleck-type ferromagnetism in a nontrivial magnetic topological insulator to Ruderman-Kittel-Kasuya-Yosida (RKKY)-type ferromagnetism in a trivial diluted magnetic semiconductor. Our work provides insights into the ferromagnetic properties of magnetically doped topological insulator thin films and facilitates the pursuit of high-temperature quantum anomalous Hall effect.