Spectroscopic perspective on the interplay between electronic and magnetic properties of magnetically doped topological insulators

• Published in: arXiv.org 2017-11
• Main Authors: Krieger, Jonas A, Cui-Zu, Chang, Marius-Adrian Husanu, Sostina, Daria, Ernst, Arthur, Otrokov, Mikhail M, Prokscha, Thomas, Schmitt, Thorsten, Suter, Andreas, Maia Garcia Vergniory, Chulkov, Evgueni V, Moodera, Jagadeesh S, Strocov, Vladimir N, Zaher Salman
• Format: Article
• Language: English
• Subjects: Antimony; Bismuth; Coherent potential approximation; Ferromagnetism; Impurities; Magnetic properties; Magnetic transitions; Muon spin rotation; Photoelectric emission; Quantum Hall effect; Tellurium; Topological insulators; Topology; Weight
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1710.06238

We combine low energy muon spin rotation (LE-\(\mu\)SR) and soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES) to study the magnetic and electronic properties of magnetically doped topological insulators, (Bi,Sb)\(_2\)Te\(_3\). We find that one achieves a full magnetic volume fraction in samples of (V/Cr)\(_x\)(Bi,Sb)\(_{2-x}\)Te\(_3\) at doping levels x \(\gtrsim\) 0.16. The observed magnetic transition is not sharp in temperature indicating a gradual magnetic ordering. We find that the evolution of magnetic ordering is consistent with formation of ferromagnetic islands which increase in number and/or volume with decreasing temperature. Resonant ARPES at the V \(L_3\) edge reveals a nondispersing impurity band close to the Fermi level as well as V weight integrated into the host band structure. Calculations within the coherent potential approximation of the V contribution to the spectral function confirm that this impurity band is caused by V in substitutional sites. The implications of our results on the observation of the quantum anomalous Hall effect at mK temperatures are discussed.