Pressure-Induced Collapse of Valence Orderand Emergence of Quantum Valence Fluctuation in YbPd

To clarify a high-pressure cubic valence fluctuating ground state of YbPd appearing after collapse of valence order, powder X-ray diffraction and electrical resistivity under high pressures were measured at low temperatures. Tracing splitting of a (4 0 0) Bragg peak manifests that the structural phase transition into a tetragonal symmetry is shifted linearly to 20 K at P = 4.4 GPa and is suppressed at P = 5.0 GPa. The resistivity measurements reveal non-Fermi liquid