Transport, AC-Susceptibility and PQR Measurements of Strongly Electron Correlated Compound YbInCu₄ at High Pressures

We have investigated physical properties of the valence fluctuating compound YbInCu₄ at high pressures and low temperatures. The first-order valence transition temperature T_V ~ 42 K at ambient pressure is completely suppressed for pressures above 2.49 GPa. Present electrical resistivity data in the pressure-stabilized high-temperature (HT) phase exhibit successive shoulders at around 20 and 2.4 K. The former can reasonably be compared with the Kondo temperature T_K ~ 25 K estimated from the static-susceptibility data at ambient pressure. For pressures above 2.27 GPa, the ac-susceptibility showed a clear peak at 2.4 K, which can be explained as the onset of a long-range ferromagnetic ordering. ⁶³Cu pure-quadrupole-resonance in the HT phase showed that the value of spin-lattice relaxation time T₁ and the almost T-independent behavior are hardly affected with pressure up to 1.3 GPa, in contrast to the large increase in quadrupole frequency.