High Field X-ray Diffraction Study on a Magnetic-Field-Induced Valence Transition in YbInCu4

We report the first high-field x-ray diffraction experiment using synchrotron x-rays and pulsed magnetic fields exceeding 30 T. The lattice deformation due to a magnetic-field-induced valence transition in YbInCu 4 is studied. It has been found that the Bragg reflection profile at 32 K changes significantly at around 27 T due to the structural transition. In the vicinity of the transition field, the low field and high field phases alternate with the discontinuous change in the lattice constant. Thus, it is evident that the field-induced valence state transition is a first-order phase transition. The field dependence of the low-field-phase Bragg peak intensity is found to be roughly scaled with the magnetization.