Anisotropic CE-type orbital correlations in the ferromagnetic metallic phase of Nd1/2Sr1/2MnO3 -: art. no. 184407

We present hard x-ray scattering studies of the charge and orbital ordering in Nd1/2Sr1/2MnO3 together with magnetization and thermal expansion measurements as a function of temperature and magnetic field. Superstructure reflections corresponding to the orbital ordering below T(CO)similar or equal to160 K are observed in the ferromagnetic metallic phase up to 200 K. The correlation length of the observed structural modulations is found to be highly anisotropic; i.e., the correlations exist predominantly in the ab planes. Moreover, the periodicity of the superstructure modulations is the same above and below T-CO. As a consequence, the modulations found in the ferromagnetic metallic phase are incommensurate to the average lattice structure. The results from hard x-ray scattering, thermal expansion, and magnetization studies can be consistently interpreted in terms of short-range orbital ordering in the ferromagnetic metallic phase of Nd1/2Sr1/2MnO3 .