Temperature dependence of the ferromagnetic response in CrxSb2-xTe3 topological insulator thin films investigated using terahertz spectroscopy and magneto-transport.

Varun S. Kamboj; Angadjit Singh; Lukas Jakob; Liam B. Duffy; Noorhayati Idros; Satyaprasad P. Senanayak; Adrian Ionescu; Harvey E. Beere; Crispin H. W. Barnes; Thorsten Hesjedal; David A. Ritchie

doi:10.1117/12.2503102

1 March 2019 Temperature dependence of the ferromagnetic response in Cr_xSb_2-xTe₃ topological insulator thin films investigated using terahertz spectroscopy and magneto-transport

Varun S. Kamboj, Angadjit Singh, Lukas Jakob, Liam B. Duffy, Noorhayati Idros, Satyaprasad P. Senanayak, Adrian Ionescu, Harvey E. Beere, Crispin H. W. Barnes, Thorsten Hesjedal, David A. Ritchie

Author Affiliations +

Proceedings Volume 10917, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XII; 109171T (2019) https://doi.org/10.1117/12.2503102
Event: SPIE OPTO, 2019, San Francisco, California, United States

Abstract

Introducing a magnetic dopant into a topological insulator can give rise to ferromagnetic ordering which can break timereversal symmetry, realizing dissipationless electronic states in the absence of an external magnetic field. Assessment and control of the magnetic state can translate into novel future applications in quantum computing. We provide a detailed study of the magnetic state in Cr doped Sb₂Te₃ thin films using terahertz time-domain spectroscopy (THz-TDS) and electrical transport. The temperature dependent behavior of the THz conductance of Cr_xSb_2-xTe₃ thin films with x = 0.15 exhibits a clear insulator-metal transition at 40 K, indicating the onset of ferromagnetic order in the Cr_xSb_2-xTe₃ at the TC (40 K). Moreover, the magneto-transport measurements showed anomalous Hall behavior below 40 K, demonstrating the consistency between the electrical and optical measurements. The direct correlation obtained between the carrier density and ferromagnetism in the magnetically doped topological insulators films, using the THz optical technique, strongly suggests a carrier-mediated RKKY coupling scenario. Our non-contact method of using THz radiation to investigate ferromagnetism and the consistency between optical and electrical measurements pave the way to realise exotic quantum states for spintronic and low energy magneto-electronic device applications.

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Varun S. Kamboj, Angadjit Singh, Lukas Jakob, Liam B. Duffy, Noorhayati Idros, Satyaprasad P. Senanayak, Adrian Ionescu, Harvey E. Beere, Crispin H. W. Barnes, Thorsten Hesjedal, and David A. Ritchie "Temperature dependence of the ferromagnetic response in Cr_xSb_2-xTe₃ topological insulator thin films investigated using terahertz spectroscopy and magneto-transport", Proc. SPIE 10917, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XII, 109171T (1 March 2019); https://doi.org/10.1117/12.2503102

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