Figure 1: Structural and magnetic properties of V-doped Sb2Te3.
From: Dual nature of magnetic dopants and competing trends in topological insulators
(a) Vanadium bulk-doped Sb2Te3 single crystal (Sb1.985V0.015Te3); (b) Sb2Te3 crystal structure: V atoms (green) are located in the second and fourth layer, substituting Sb; (c) 75 × 75 nm2 topographic image showing the absence of any clustering; (d) high-resolution image showing the V substitutional sites. Triangular depressions labelled as A and B correspond to the two possible V substitutional sites located in the second and fourth layer, respectively; (e) schematic of XMCD measurements. Photons with well-defined circular polarization and energy are absorbed by the sample in a variable magnetic field. The resulting photocurrent (total electron yield (TEY)) is measured, making the technique sensitive to surface magnetism. (f) TEY signals for opposite magnetic fields (blue and red lines) of B=±1 T. Their difference (green line) sheds light on the magnetic response of the V dopants; (g) out-of-plane V-L3 XMCD magnetization curve: the square shape of the hysteresis loop proves the existence of long-range surface ferromagnetic order.
