The pressure and temperature phase diagram of YbInCu4 has been investigated by nuclear quadrupolar resonance (NQR) and spin-lattice relaxation rate (T1-1) experiments. The pressure dependence of the Cu63 NQR frequency indicates that the first-order valence transition temperature, Tv, does not vanish continuously at the critical pressure (Pc≈23.7kbar) and thus there is no quantum critical point (Tv=0) in YbInCu4. This result is consistent with the T1-1 data, which show no evidence for non-Fermi-liquid behavior near Pc. For pressures P Pc, T1-1 increases sharply near 2.4K, which suggests the presence of critical fluctuations associated with ferromagnetic (FM) ordering. We analyze the T1-1, resistivity, and the pressure-enhanced susceptibility data in the mixed-valent state of YbInCu4 and find no evidence to indicate that the pressure-induced FM phase can be described by the Stoner theory for itinerant ferromagnetism. Rather, the pressure-induced FM order may be due to pressure-stabilized Yb3+ local moments. We also examine the possibility of FM order induced by an external magnetic field near Pc, but find no evidence down to 1.5K.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 1 Jun 2005|