Extracting d-orbital information from Magnetic Compton experiments in bilayer manganites

Magnetic Compton profiles (MCPs) have been measured for the colossal magnetoresistance double layer manganite La$_{1.2}$Sr$_{1.8}$Mn$_2$O$_7$ along various crystallographic directions over a wide range of temperatures and magnetic fields. The experimental results are interpreted via first-principles computations of the magnetic momentum density and the MCPs. The usefulness of the so called $B({\bf r})$ function, obtained by a one-dimensional Fourier transform of the MCP, is emphasized [1]. In particular, the form of $B({\bf r})$ for momentum transfer along the [110] direction is found to contain a prominent dip at around 1 a.u., whose depth is shown to provide a sensitive measure of the population of $e_g$ electrons of $d_{x^2-y^2}$ symmetry in the system. Work supported in part by the USDOE.\\ $\mbox{[1]}$ Yinwan Li, P. A. Montano, J.F. Mitchell, B. Barbiellini, P. E. Mijnarends, S. Kaprzyk and A. Bansil, Phys. Rev. Lett. {\bf 93}, 207206 (2004).