The material sandwiches together individual layers of atoms, producing a thin film with magnetic polarity that can be flipped from positive to negative or vice versa with small pulses of electricity. Device-makers could potentially use this property to store digital 0s and 1s.
"Before this work, there was only one other room temperature multiferroic whose magnetic properties could be controlled by electricity," said assistant professor John Heron.
Room-temperature multiferroics are said to require much less power to read and write data than today's semiconductor-based devices. In addition, their data doesn't vanish when the power is shut off. Those properties could enable devices that require only brief pulses of electricity instead of the constant stream that's needed for current electronics, using an estimated 100 times less energy.
To create the new material, the researchers started with thin, atomically precise films of hexagonal lutetium iron oxide (LuFeO3), a material known to be a robust ferroelectric, but not strongly magnetic. LuFeO3 consists of alternating monolayers of lutetium oxide (Lu2O3) and iron oxide (Fe2O3). They then used molecular-beam epitaxy to add one extra monolayer of Fe2O3 to every 10 atomic repeats of the single single monolayer pattern.
The result was a new material that combines a phenomenon in Lu2O3 called ‘planar rumpling’ with the magnetic properties of Fe2O3 to achieve multiferroic properties at room temperature.
Heron explained that the lutetium exhibits atomic-level displacements called rumples. Visible under an electron microscope, the rumples enhance the magnetism in the material, allowing it to persist at room temperature. The rumples can be moved by applying an electric field, and are enough to nudge the magnetic field in the neighbouring layer of Fe2O3 from positive to negative or vice versa, creating a material whose magnetic properties can be controlled with electricity.
