Publication Details

Cortie, D, Zhao, W, Yue, Z, Li, Z, Bake, A, Marenych, O, Pastuovic, Z, Nancarrow, M, Zhang, Z, Qi, D-C, Evans, P, Mitchell, DRG & Wang, X 2020, ‘Creating thin magnetic layers at the surface of Sb2Te3 topological insulators using a low-energy chromium ion beam’, Applied physics letters, vol. 116, no. 19, p. 192410.


The surfaces of Sb2Te3 topological insulator crystals were implanted using a 40 keV chromium ion beam. To facilitate uniform doping, the Sb2Te3 was passivated with a thin TiO2 film before the implantation step. The resulting chemical structure was studied using atomic-resolution transmission electron microscopy. A fluence of 7 × 1015 ions/cm2 at 40 keV lead to amorphization of the Sb2Te3 surface, with chromium predominantly incorporated in the amorphous layer. Heating to 200 °C caused the amorphous region to recrystallize and led to the formation of a thin chromium-rich interfacial layer. Near-edge x-ray absorption spectroscopy indicates a uniform valence state of Cr3+ throughout, with no evidence of metallic clustering. High-temperature superparamagnetic behavior was detected up to 300 K, with an increased magnetic moment below 50 K.

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