Hall effect in quasi-binary GdZnxCu1-x alloys with the variable sign of exchange interaction

In intermetallic GdZnxCu1-x compounds the substitution of Zn for Cu atoms changes the negative sign of exchange interaction in GdCu (TN = 144 K) to positive one in GdZn (TC = 268 K). The phase transition between antiferromagnetic (A) and ferromagnetic (F) states takes place at concentrations 0.2 < x < 0.8 where at low temperatures both antiferromagnetic and ferromagnetic phases are present. The investigations of the galvanomagnetic properties of the alloys under study display a rather unusual behavior of the ordinary and extraordinary Hall coefficients. The concentration dependence of R0 at T = 4.2 K has a maximum at x ∼ 0.5. In these alloys the R0(x) dependence actually correlates with the concentration dependence of the residual electrical resistivity ρ(x). Such a consistency between R0(x) and ρ(x) was obtained for multiphase systems in the effective medium model. The extraordinary Hall coefficient can be separated only at concentrations where the F-phase is present. Rs increases abruptly near the concentration threshold for the appearance of the ferromagnetic subsystem (xF ∼ 0.2.). (orig.)