Exchange bias refers to the shift of the magnetic hysteresis loop of a ferromagnet, which is caused by the hard magnetization of an antiferromagnet that is in contact with it. Although exchange bias is tremendously important because of its potential technological applications in spintronics, the coupling mechanism behind the exchange bias is still an open question and its full control has not been achieved.
Here we are particularly interested in the exchange bias (spin coupling) between two perovskite oxide materials, BiFeO3 (BFO, a multiferroic with ferroelectric polarization and antiferromagnetism coupled together) and La0.7Sr0.3MnO3 (LSMO, a ferromagnetic with well-known colossal Magnetoresistance effect). When these two materials interact with each other, the resulting fascinating physics involving spin, charge and orbital will allow us to study various external tuning parameters on the effect of the exchange bias and to reveal the essential coupling mechanism responsible. Moreover, because of the coupling between ferroelectricity and antiferromagnetism in BFO, this system also offers a great opportunity to study the electric field effect on exchange bias and eventually to achieve an electric field control of ferromagnetism, which is a possible renaissance of the traditional spintronics.
|
