Changes in the local structure of a La0.70Ca0.30MnO3 CMR sample induced by a magnetic field

We investigated the effect of an applied magnetic field on the local distortions of MnO6 octahedra in a La0.70Ca0.30MnO3 colossal magnetoresistive ~CMR! sample. Previously we have shown that the variance s(T) for the Mn-O pair distribution function is a function of the magnetization M (T); however, 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 s 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 polarization vector P. Our measurements verify that the local distortion does indeed change with B near Tc , as expected.