The pressure dependence of the transport properties of YBa₂Cu₃O_7-δ

Abstract

The authors have measured the normal-state transport properties of sintered samples of YBa2Cu3O7- delta as a function of temperature and at pressures up to 8 kbar. The room-temperature resistivity decreases at -1.0% kbar-1. The Hall coefficient has a value of 2.8*10-9 m3 C-1 at room temperature, rising to 7.8*10-9 m3 C-1 just above the superconducting transition temperature. This gives an effective carrier concentration of 0.4 holes per unit cell at room temperature. In contrast to the strong temperature dependence of RH, the pressure dependence is very weak ( mod dRH/dP mod <1% kbar-1) and they show that this is inconsistent with the temperature dependence if we assume a simple volume dependence of RH. They discuss models for the Hall coefficient and consider that its temperature dependence is determined by the low-dimensional character of the energy bands near the Fermi energy.