Giant Inverse Tunneling Magnetoresistance in Single CrO_2/Vacuum/Ni_80Fe_20 Using Conductive AFM

摘要

The chromium dioxide (CrO_2) is a half metallic ferromagnet which has both the metallic and semiconductive spin bands[1,2,3]. This material has been intensively investigated, because these half metallic spin bands induce the applications such as an enormously sensitive magnetic sensor and a MRAM etc. It was recently reported that the tunneling magnetoresistance (TMR) measurements in CrO_2/I/Co junctions showed the inverse TMR effects with the values of the TMR ratio of -24% and -1% at 5K and the room temperature, respectively by J. S. Parker et. al.[4]. The recent band calculations[5] support this inverse TMR effects, although the negative sign of the TMR is probably due to the insulator and/or Co. However, these values of the ratio are too small compared with the values expected theoretically in the junction using the half metal. The roughness of the interface between both layers probably reduces the values of the TMR ratio.