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Temperature dependence of the ferromagnetic response in CrxSb2-xTe3 topological insulator thin films investigated using terahertz spectroscopy and magneto-transport.
Author(s): 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
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Paper 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 CrxSb2-xTe3 thin films with x = 0.15 exhibits a clear insulator-metal transition at 40 K, indicating the onset of ferromagnetic order in the CrxSb2-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.

Paper Details

Date Published: 1 March 2019
PDF: 9 pages
Proc. SPIE 10917, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XII, 109171T (1 March 2019); doi: 10.1117/12.2503102
Show Author Affiliations
Varun S. Kamboj, Univ. of Cambridge (United Kingdom)
Angadjit Singh, Univ. of Cambridge (United Kingdom)
Lukas Jakob, Univ. of Cambridge (United Kingdom)
Univ. of Tuebingen (Germany)
Liam B. Duffy, Univ. of Oxford (United Kingdom)
Noorhayati Idros, Univ. of Cambridge (United Kingdom)
Satyaprasad P. Senanayak, Univ. of Cambridge (United Kingdom)
Central Institute of Plastics Engineering and Technology (India)
Adrian Ionescu, Univ. of Cambridge (United Kingdom)
Harvey E. Beere, Univ. of Cambridge (United Kingdom)
Crispin H. W. Barnes, Univ. of Cambridge (United Kingdom)
Thorsten Hesjedal, Univ. of Oxford (United Kingdom)
David A. Ritchie, Univ. of Cambridge (United Kingdom)

Published in SPIE Proceedings Vol. 10917:
Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XII
Laurence P. Sadwick; Tianxin Yang, Editor(s)

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