Effect of pressure on transport properties of mixed-valence compound YbAl3

The pressure effects on the electrical resistivity and the Hall effect have been measured for YbAl3 and LuAl3. LuAl3 is a normal metal and has negative pressure coefficient of resistivity -5X10(-3) kbar(-1) at room temperature, which is explained by a phonon stiffening effect. In the mixed-valence compound YbAl3, the magnetic contribution to the resistivity is increased by pressure. The Gruneisen parameter of the Kondo temperature Omega (K) = -partial derivative In T-K/partial derivative In V is estimated -7 for YbAl3 from the coefficient of the quadratic temperature dependence of the resistivity at low temperatures. The decrease of T-K with pressure indicates that the density of conduction electron states at the Fermi energy and/or the exchange of 4f and conduction electrons are suppressed by pressure in YbAl3. (C) 2001 Elsevier Science B.V. All rights reserved.