Magnetic proximity-enhanced Curie temperature of Cr-doped Bi2Se3 thin films
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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 ≈ 7K 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 ∼19K, while in the bulk it rises to ∼10K. 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.
Baker , A A , Figueroa , A I , Kummer , K , Collins-McIntyre , L J , Hesjedal , T & van der Laan , G 2015 , ' Magnetic proximity-enhanced Curie temperature of Cr-doped Bi 2 Se 3 thin films ' , Physical Review. B, Condensed matter and materials physics , vol. 92 , no. 9 , 094420 . https://doi.org/10.1103/PhysRevB.92.094420
Physical Review. B, Condensed matter and materials physics
© 2015 American Physical Society. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at http://dx.doi.org/10.1103/PhysRevB.92.094420
DescriptionBeam time awarded on ID32 at the ESRF (Proposal No. HC-1282) and on I10 at the Diamond Light Source (Proposal No. SI-10207) are acknowledged. T.H. acknowledges the John Fell Oxford University Press (OUP) Research Fund. A.A.B. was supported by Diamond Light Source and together with L.J.C.M. by EPSRC through Doctoral Training Awards.
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