The team, which includes researchers from the University of Sydney, Australian National University, the University of Akron and the University of Wollongong, uses a sol-gel method in combination with electrospinning to assemble and organize the fine-grained structures of BiFeO3 into fibres. Electrospinning allows the researchers to control the size of BiFeO3 particles and collect aligned fibrous structures, which opens the door to building novel nanoscale electronic devices. The BiFeO3 fibres display sizeable M versus H hysteresis loops; that is, the fibres show ferromagnetism at room temperature. The non-linear M versus H relationship is accompanied by a coercivity of ~250 Oe and 1.34 emu/g saturation magnetization. The size of the individual particles in the fibres was ~30 nm, which is much smaller than the size of the spiral ordering (~62 nm). Hence, the fibres displayed ferromagnetic behaviour as opposed to weak magnetization displayed by bulk BiFeO3. Furthermore, the piezoresponse of the fibre was measured and the local polarization and domain structures within the fibres were determined.

The amplitude versus voltage loops recorded for the fibre display a butterfly shape, which is a typical characteristic of ferroelectric material. Thus, the ferromagnetic and ferroelectric behaviour of the fibre was confirmed.

More details can be found in the journal Nanotechnology.