MIXED-STATE SPECIFIC-HEAT OF THE TYPE-II SUPERCONDUCTOR NB0.77ZR0.23 IN MAGNETIC-FIELDS UP TO B-C2

In order to document the behavior of the mean-field mixed-state specif ic heat of an isotropic, strongly type-II superconductor tie., with a large value of the Ginzburg parameter kappa), and to provide a basis f or comparison with high-temperature superconductors, we measured the s pecific heat C of the alloy Nb0.77Zr0.23 with T-c = 10.8 K, B-c2(0) =7 .9 T, in magnetic fields B = 0, 0.2, 1.0, 1.2, 2.0, 2.4, 3.0, 3.3, 4.0 , 4.4, 4.8, 5.2, 6.0, 6.6, 7.2 and 10 T. The values of the upper criti cal field B-c2(T), thermodynamic critical field B-c(T), Ginzburg param eter kappa(T), and coefficient gamma(B)=lim(T-->0)(C(T,B)/T) are deriv ed from the specific heat data and found to be in agreement with the G LAG theory in the dirty limit. The behavior of the mixed-state specifi c heat is analyzed in terms of C-el/T,partial derivative(C-el/T)/parti al derivative B, and partial derivative(C-el/T)/partial derivative T v s. T curves, where C-el is the electronic contribution to the specific heat.