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Published online: 4 November 2009 | doi:10.1038/nchina.2009.214

Nanomaterials: Spintronic snowflakes

Felix Cheung

Introduction

© (2009) AIP

Dilute magnetic semiconductors (DMSs) are doped semiconductors that exhibit ferromagnetism at room temperature. They have attracted a lot of attention recently because of their potential applications in spintronics. Qiliang Cui and co-workers at Jilin University in Changchun¹ have now prepared DMS nanostructures with hexagonal symmetry — like that of snowflakes.

The researchers heated aluminium and scandium powders in an electric arc furnace filled with nitrogen gas. After 20 minutes, a layer of grey flaky nanocrystals had formed on the cathode surface.

Using energy-dispersive X-ray spectroscopy, the team confirmed the chemical composition of the crystals to be scandium-doped aluminium nitride (aluminium nitride is a well-known semiconductor). X-ray crystallography then revealed that the crystals exhibited hexagonal symmetry, giving the crystals a well-defined hierarchical structure that could be observed by scanning electron microscopy (pictured). The 'snowflake' structure comprises a backbone with nanowires branching outwards.

The researchers also studied the magnetic properties of the crystals. They observed a hysteresis loop — the signature of ferromagnetism — at 300 K. The results suggest that scandium is a potential non-magnetic dopant for preparing DMS materials.

The authors of this work are from:
State Key Laboratory of Superhard Materials, Jilin University, Changchun, China.

Reference

1. Lei, W. W. et al. Ferromagnetic Sc-doped AlN sixfold-symmetrical hierarchical nanostructures. Appl. Phys. Lett. 95, 162501 (2009). | Article