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Magnetic proximity-enhanced Curie temperature of Cr-doped Bi2Se3 thin films

DOI: 10.1103/PhysRevB.92.094420 DOI Help

Authors: A. A. Baker (Diamond Light Source) , A. I. Figueroa (Diamond Light Source) , K Kummer (European Synchrotron Radiation Facility (ESRF)) , L. J. Collins-mcintyre (University of Oxford) , T. Hesjedal (Diamond Light Source) , G. Van Der Laan (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 92 (9) , PAGES 094420

State: Published (Approved)
Published: September 2015
Diamond Proposal Number(s): 10207

Abstract: We report a study on the transition temperature TC of Cr-doped topological insulator thin films, where an increase in the ferromagnetic onset can provide a pathway towards low-power spintronics in the future. Arrott plots, measured by surface-sensitive x-ray magnetic circular dichroism at the Cr L2,3 edge as a function of field at various low temperatures, give a TC ≈ 7 K for the pristine surface. This is comparable to the bulk value of the film, which means that there is no indication that the spontaneous magnetization is different near the surface. Evaporation of a thin layer of Co onto the pristine surface of the in-situ cleaved sample increases the ordering temperature near the surface to ∼19 K, while in the bulk it rises to ∼10 K. X-ray absorption spectroscopy shows that Cr enters the Bi2Se3 host matrix in a divalent state, and is unchanged by the Co deposition. These results demonstrate a straightforward procedure to increase the transition temperature of doped topological insulators.

Journal Keywords: XMCD; Topological Insulators

Subject Areas: Physics, Materials, Energy

Instruments: I10-Beamline for Advanced Dichroism

Other Facilities: ESRF Grenoble