Multiferroic at room temperature
The researchers produced this multiferroic material by vapour coating ultra-thin ferromagnetic iron layers onto ferroelectric bismuth-titanium oxide layers. In so doing, they were able to establish that the otherwise non-magnetic ferroelectric material becomes ferromagnetic at the interface between the two ferromagnetic layers. Thus, the researchers have developed the world's first multiferroic material that reacts to both magnetic and electric fields at room temperature.
Magnetic X-ray scattering throws light on new control mechanism
The scientists demonstrated this interfacial magnetism using the spectroscopic method "X-ray magnetic circular dichroism". In this method, the polarisation of the X-rays is affected by magnetism in a way which is similar to the famous "Faraday effect" in optics. X-ray magnetic circular dichroism has the advantage that it can be applied to every single element in the material investigated. With this method, the researchers were able to show that all three elements in the ferroelectric material - bismuth, oxygen and titanium - react ferromagnetically at the interface to iron, although these atoms are otherwise not magnetic.
An extremely sophisticated method
"The method of X-ray magnetic circular dichroism is highly complex", said Prof. Dr. Hartmut Zabel, Chair of Experimental Physics at the RUB. The measuring chamber ALICE combines X-ray scattering with X-ray spectroscopy. "This is an extremely sophisticated and very sensitive method", explained Prof. Zabel. "The high precision of the detectors and all the goniometers in the chamber led to the success of the experiments conducted by the international measuring team."
|Contact: Professor Dr. Hartmut Zabel|