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MA: Fachverband Magnetismus

MA 4: Topological Insulators 1 (jointly with DS,HL,O,TT)

MA 4.2: Vortrag

Montag, 11. März 2013, 10:00–10:15, H10

Magnetic properties of the Mn doped topological insulator Bi₂Te₃ probed by ESR — •S. Zimmermann¹, V. Kataev¹, Huiwen Ji², R.J. Cava², and B. Büchner¹ — ¹IFW Dresden, 01171 Dresden, Germany — ²Dept. Chem., Princeton Univ., NJ 08544, USA

Doping of a topological insulator (TI) with magnetic elements can break the time reversal symmetry and thus open a gap in the protected spin polarized conducting surface states, driving the system into a quantum spin Hall regime [1]. Understanding of the interactions between localized magnetic moments of dopants via delocalized electrons that give rise to ferromagnetism in TIs is therefore of significant interest. Such interactions can be of a long-range character and can also be mediated by surface conducting states [2]. Electron Spin Resonance (ESR) spectroscopy is a sensitive local technique that can probe interactions of localized spins with conduction electrons as well as spin-spin interactions in semiconductors and metals. In this contribution we report an ESR study of the Mn spin dynamics and magnetic interactions in high-quality single crystals of the Mn doped 3-dimensional TI Bi₂Te₃ [3]. We have observed a well-defined ESR signal from Mn spins and have studied the temperature dependences of the ESR parameters for a set of Bi₂Te₃ crystals with different Mn doping levels. The experimental ESR data will be presented in detail and the doping dependence of the Mn spin relaxation via conducting states and the establishment of ferromagnetic order as seen by ESR will be discussed. [1] R. Yu et al., Science 369, 61 (2010); [2] L.A. Wray et al., Nature Physics 7, 32 (2011); [3] Y.S. Hor et al., PRB 81, 195203 (2010)