Sign reversal of the Hall effect in YBa2(Cu1?x )3O7?? single crystals

TLDR: In this paper, the authors measured the in-plane Hall effect and resistivity of cobalt-doped YBa2Cu3O7−δ (YBCO) single-crystal samples.

Abstract: We have measured the in-plane Hall effect and in-plane resistivity of cobalt-doped YBa2Cu3O7−δ (YBCO) single-crystal samples. The concentration of cobalt ranged from 1 to 3%. As the applied field was varied, a sign reversal of the Hall resistivity was seen for 1 and 2% Co-doped samples, but not for the 3% sample. Our results are expressed in terms of conductivities, as recently recommended by the work of Dorseyet al. and Kopninet al. In the mixed state just below the superconducting transition temperatureTc, the Hall conductivityσxy is the sum of two terms,C1/H andC2H, whereC1 andC2 are field-independent but temperature-dependent. As previously observed by Ginsberg and Manson for undoped YBCO, the coefficientC1 is approximately proportional toτ2 andC2 is approximately linear inτ, whereτ = 1−(T/T c ). The values ofC1 andC2 are presented for each cobalt concentration.