Magnetic ordering in Ho-doped Bi2Te3 topological insulator
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We investigate the magnetic properties of Ho-doped Bi2Te3 thin films grown by molecular beam epitaxy. Analysis of the polarized X-ray absorption spectra at the Ho M5 absorption edge gives an effective 4f magnetic moment which is ∼45% of the Hund's rule ground state value. X-ray magnetic circular dichroism (XMCD) shows no significant anisotropy, which suggests that the reduced spin moment is not due to the crystal field effects, but rather the presence of non-magnetic or antiferromagnetic Ho sites. Extrapolating the temperature dependence of the XMCD measured in total electron yield and fluorescence yield mode in a field of 7 T gives a Curie-Weiss temperature of θ CW ≈ -30 K, which suggests antiferromagnetic ordering, in contrast to the paramagnetic behavior observed with SQUID magnetometry. From the anomaly of the XMCD signal at low temperatures, a Néel temperature TN between 10 K and 25 K is estimated.
Figueroa , A I , Harrison , S E , Collins-Mcintyre , L J , van der Laan , G & Hesjedal , T 2016 , ' Magnetic ordering in Ho-doped Bi 2 Te 3 topological insulator ' Physica Status Solidi - Rapid Research Letters , vol 10 , no. 6 , pp. 467-470 . DOI: 10.1002/pssr.201600061
Physica Status Solidi - Rapid Research Letters
© 2016, Wiley-VCH Verlag GmbH & Co . This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at onlinelibrary.wiley.com / https://dx.doi.org/10.1002/pssr.201600061
This publication arises from research funded by the John Fell Oxford University Press (OUP) Research Fund and the Research Complex at Harwell is acknowledged for their hospitality. SEH acknowledges partial financial support from a DARPA MESO Project (No. N66001-11-1-4105) and the VPGE (Stanford University) and LCM partial financial support from EPSRC (UK) through a Doctoral Training Award.
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