Magnetization process and the associated lattice deformations in an intermetallic compound Gd5Ge3

The results of magnetization and synchrotron X-ray diffraction measurements on Gd5Ge3 subject to a pulsed high magnetic field are reported. When the magnetic field, H, is applied parallel to the a-axis, a sudden increase in magnetization, M, has been observed at ∼3.8 T. For H parallel c, M increases monotonically with H. The magnetization becomes saturated above about 30T for the two orientations. The lattice constant, a elongates, while c shrinks with increasing H. We calculate the exchange energy under applied magnetic fields based on the proposed magnetic structure assuming an antiferromagnetic exchange interaction in the a-a plane and a ferromagnetic one along the c-axis. We are successful in explaining the opposing behavior of the lattice deformations. Our calculation shows that the change in the lattice constants is proportional to M2, in agreement with the observation. (author)