Researchers from Germany, France and the United Kingdom have engineered a material that exhibits a rare and versatile trait in magnetism at room temperature.
Writing in the journal Nature Materials, the team explain how this unique ‘multiferroic’ property present in the material could potentially be fashioned for use in quick and cost-effective data storage. A multiferroic material has both the ability to be electrically (ferroelectric) as well as magnetically (ferromagnetic) charged. Its magnetisation is controlled by electricity.
Diffractometer (Helmholtz Centre Berlin for Materials and Energy)
The material this research was based around is known as barium titanate – BaTiO3. The team were able to witness the dual traits of both ferroelectric and ferromagnetic in the thin films of BaTiO3 thanks to a research method known as soft X-ray resonant magnetic scattering.
‘We’ve shown a way where you can obtain a multiferroic at room temperature,’ says lead researcher Sergio Valencia from the Helmholtz Centre Berlin for Materials and Energy. ‘Barium titanate is ferromagnetic, so it means you have a net-magnetic moment you can really control by an electric field. The idea is that you can apply a voltage to the ferroelectric reversing the ferroelectric polarization which in turn affects the magnetization of your film. You can use this for example to write bits of information in memories of computers by only applying voltages, which is much cheaper in terms of power than traditionally applying magnetic fields.’
This is why being able to control a material’s magnetism at room temperature is more cost-efficient whereas controlling current multiferroic materials is much more complicated.
The team hope that their findings will reduce the scarcity of these types of multiferroics. The two traits ferromagnetic and ferroelectric have a tumultuous relationship. The conditions that a ferromagnetic requires to exist are unfortunately not the same as those required by a ferroelectric. However, at the same time they both complement each other and affect each other’s behaviour.
‘They are scarce and the problem is that most of them are multiferroic only at very low temperatures,’ comments Sergio Valencia. ‘Therefore they are not useful for applications. If you have to go to 270 °C for a multiferroic then it’s really complicated and expensive to implement them in room temperature working devices.’
