Changes in the local structure of a La0.70Ca0.30MnO3CMR sample induced by a magnetic field

We investigated the effect of an applied magnetic field on the local distor tions of MnO6 octahedra in a La0.70Ca0.30MnO3 colossal magnetoresistive (CM R) sample. Previously we have shown that the variance sigma(2)(T) for the M n-O pair distribution function is a function of the magnetization M(T); how ever, in the earlier study, each point is at a different temperature. Since an external magnetic field directly controls the sample magnetization, we expect to observe a corresponding change in sigma(2) of a CMR sample when a magnetic field B is applied at a fixed temperature. Two field-orientations were used with B parallel and perpendicular (horizontally) to the x-ray po larization vector P. Our measurements verify that the local distortion does indeed change with B near T-c, as expected.