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Archive of Highlights Highlights Vol. 47 No.5-6 - Highlights A New High for Magnetically Doped Topological Insulators (Vol. 47 No. 5-6)

A New High for Magnetically Doped Topological Insulators (Vol. 47 No. 5-6)

Temperature dependence of the magnetization, M(T), of CrxSb2-xTe3 thin film samples with varying Cr concentration, x. The most highly doped and structurally uncompromised film shows a transition temperature of 125 K

Topological insulators (TIs) are a new phase of quantum matter whose conducting surface states are a result of the topology of their bulk band structure. Their spin-momentum locked topological surface states are resilient to backscattering owing to their protection by time-reversal symmetry (TRS). These properties make them intriguing candidates for low-power devices, spintronics and quantum computation. Breaking TRS by introducing magnetic dopants, and introducing a gap in the topological surface states, unlocks exotic quantum phenomena such as the quantum anomalous Hall state. Doping TIs with magnetic impurities is an experimentally challenging process and most TI materials only exhibit magnetic ordering at low temperatures.

In this study, using a variety of complementary structural, electronic and magnetic characterisation techniques, we demonstrate the synthesis of magnetically doped TI thin films with high structural quality. The Cr-doped Sb2Te3 thin films were grown on sapphire using low-temperature molecular beam epitaxy. We show that this particular system exhibits uniform ferromagnetic ordering up to ~125 K – a step forward towards device-friendly TI materials.

L. J. Collins-McYntire + 13 co-authors, Structural, electronic, and magnetic investigation of magnetic ordering in MBE-grown CrxSb2-xTe3 thin films, EPL 115, 27006 (2016)
[Abstract]