Ca$_{3}$(Ru$_{1-x}$Cr$_{x}$)$_{2}$O$_{7}$: A new paradigm for spin valves*

A spin valve is a device structure whose electrical resistance can be manipulated by controlling the relative spin alignment of adjacent metallic, magnetic layers separated by nonmagnetic insulating layers. The spin valve effect is a quantum phenomenon so far only realized in multilayer thin films or heterostructures. Here we report a \textit{novel}, \textit{strong} spin valve effect existing in \textit{bulk} single crystals of Ca$_{3}$(Ru$_{1-x}$Cr$_{x})_{2}$O$_{7}$ having an anisotropic, bilayered crystal structure [1]. This discovery opens new avenues to understand the underlying physics of spin valves, and fully realize its potential in practical devices. \\[4pt] [1] G. Cao, V. Durairaj, S. Chikara, and L.E. DeLong and P. Schlottmann, \textit{Phys. Rev. Lett.} \textbf{100}, 016604 (2008)