Thermally induced rotation of 3d orbital stripes in Pr(Sr0.1Ca0.9)2Mn2O7.

Abstract

We have investigated orbital ordering in the bilayer manganite, Pr(Sr0.1Ca0.9)2Mn2O7, using synchrotron x-ray diffraction techniques, in particular resonant soft x-ray diffraction. Diffraction signals are observed at (0,1/2,0) above 300 K and (1/2,0,0) below 300 K, corresponding to orbital stripes along the a and b axes, respectively. The previously observed transition at 300 K is evidence of a rotation of the orientation of the 3d orbital stripes. Large resonances of the orbital signals are observed at the Mn L edges, with a complex dependence on incident photon energy indicative of a weakly Jahn-Teller distorted system. A structural transition observed at 92 K is found not to involve a further change in the orbital order.