ANISOTROPIC PRESSURE-DEPENDENCE OF THE RESISTIVITY IN YBA2CU4O8

The anisotropic pressure dependence of the resistivity of YBa2Cu4O8 ha s been determined for the two plane directions a and b. The resistivit y in a direction, rho(a), reflecting CuO2 planes, revealed a strong pr essure dependence d lnp(a)/dp=13x10(-3) kbar(-1). In the stiffer b dir ection with two conduction channels, along CuO chains and CuO2 planes, a smaller decrease upon pressure but the strongest change with respec t to the lattice contraction was found. The pressure dependence observ ed can be explained by a charge transfer from chains to planes.