Large Room-Temperature Tunneling Magnetoresistance of “Bulrush-Like” Double Perovskite Ba $_{2}$ FeMoO

We conducted magnetic and transport measurements on two Ba₂ FeMoO₆ double perovskite samples prepared by wet chemistry and solid-state reaction methods, respectively. The one synthesized by the latter is in the form of isotropic grains. The "bulrush-like" Ba₂FeMoO₆ sample fabricated by wet chemistry is high in aspect ratio and Fe/Mo ordering. Utilizing the high shape anisotropy of the sample, we obtained a material with electric anisotropy where the long axis of the sample is almost parallel to the plane of the pellet. With carrier transport perpendicular to the plane, there was an appreciable increase in room-temperature tunneling magnetoresistance (TMR) response (from 22% to 31% at 10 kOe) while the concentration of Fe/Mo disorder remained unchanged. Experimental results indicate that the TMR value could be greatly enhanced by adjusting the nature and amount of grain boundary (GB) insulating barriers