Thin films: unexpected magnetism in a dielectric oxide.
It is generally accepted that magnetic order in an insulator requires the cation to have partially filled shells of d or f electrons. Here we show that thin films of hafnium dioxide (HfO2), an insulating oxide better known as a dielectric layer for nanoscale electronic devices, can be ferromagnetic even without doping. This discovery challenges our understanding of magnetism in insulators, because neither Hf4+ nor O2- are magnetic ions and the d and f shells of the Hf4+ ion are either empty or full.
SFI-Trinity Nanoscience Laboratory, Physics Department, Trinity College, Dublin 2, Ireland.
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M
Venkatesan
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CB
Fitzgerald
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JM
Coey