Cooperating with the National Institute for Materials Science, Japan, the Institute of Physics, CAS, the Florida International University, USA, and the Louisiana State University, USA, Prof. Ruiwei Li's group has first observed anisotropic magnetoresistance effect in a single crystal of perovskite-type manganese oxide, its value can reach more than 90 percent. They have discovered that the exceptional AMR effect is closely related to adjustable magnetic insulator-to-metal transformation in perovskite-type manganese oxides, it provides a new approach to research new AMR materials and their applications, and the research result was published in the Proceedings of the National Academy of Sciences (Early Edition) on Aug. 11, 2009.

In 1857, W. Thomson first discovered that material resistivity is changed with the direction of external magnetic field. This phenomenon is known as AMR effect. AMR effect spreads among all types of ferromagnetic materials, and has been widely applied to magnetic read heads and magnetic sensors. Comparing with GMR, TMR, CMR,the AMR value of traditional ferromagnetic materials is smaller, for example, permalloy is a wide used AMR materials, however, at room temperature its AMR value is only 1-2%. Recently the AMR devices are gradually being replaced by GMR and TMR devices. The research result has proved that in a single crystal of the perovskite-type manganese oxide, even weak anisotropy can induce AMR effect; its value is higher than GMR and TMR.