Probing unique magnetic materials

Much as some materials exhibit ferromagnetic properties, meaning they form permanent magnets, some are known to exhibit ferroelectric properties, where the material possesses a spontaneous electric polarization. Rarely, materials possess both these properties, and are known as multiferroics. Scientists working at the Diamond Light Source have now been able to probe the magnetic properties of a multiferroic using the beam line I16.

At present, many technologies such as computer hard drives and security access cards rely on magnetic materials containing coded information. The magnetic material will have this information ‘written’ onto it via electric induction, a process that requires a lot of energy. The use of a multiferroic material would allow the information to be written using an electric field, a process which would be more energy efficient.

Typically, materials tend only to be either ferromagnetic or ferroelectric, and those that are multiferroics only exhibit these properties at low temperatures. The work on I16 aimed to understand the physics of multiferroics, so that in the future they can be used for wider engineering and technological purposes. “This material is very exciting as it does demonstrate multiferroic properties at room temperature” says Roger Johnson, of Oxford University. “[The data observed] was what we’d predicted, but we wanted to measure it too. We’ve now got a direct probe of the magnetism of this material.” 

Figure: Illustration of the three magnetic domains of BiFeO3, coloured red, blue and green, imaged using non-resonant magnetic diffraction techniques at I16. The magnetic moments (spins) in each domain rotate in a common plane, and with a common sense of rotation determined by the direction of the electric polarisation, shown by the yellow arrow

DOI: 10.1103/PhysRevLett.110.217206