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.
Venkatesan
M
M
SFI-Trinity Nanoscience Laboratory, Physics Department, Trinity College, Dublin 2, Ireland.
Fitzgerald
C B
CB
Coey
J M D
JM