Pressure induced softening of YB_6: pressure effect on the Ginzburg-Landau parameter κ=λ/ξ
arXiv:cond-mat/0605391 · doi:10.1103/PhysRevLett.97.157002
Abstract
Measurements of the transition temperature T_c, the second critical filed H_{c2} and the magnetic penetration depth λunder hydrostatic pressure (up to 9.2 kbar) in the YB_6 superconductor were carried out. A pronounced and {\it negative} pressure effects (PE) on T_c and H_{c2} with dT_c/dp=-0.0547(4) K/kbar and μ_0dH_{c2}(0)/dp =-4.84(20) mT/kbar, and zero PE on λ(0) were observed. The PE on the coherence length dξ(0)/dp=0.28(2) nm/kbar was calculated from the measured pressure dependence of H_{c2}(0). Together with the zero PE on the magnetic penetration depth λ(0), our results imply that the Ginzburg-Landau parameter κ(0)=ξ(0)/λ(0) depends on pressure and that pressure "softens" YB_6, e.g. moves it to the type-I direction.
4 pages, 2 figures