Magnetization Process and the Associated Lattice Deformations in an Intermetallic Compound Gd5Ge3

The results of magnetization and synchrotron X-ray diffraction measurements on Gd 5 Ge 3 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 ∥ c , M increases monotonically with H . The magnetization becomes saturated above about 30 T 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 M 2 , in agreement with the observation.