Upper critical field, temperature

Fig. 20. (a) Temperature dependence of the upper critical field calculated within a two-band model for several impurity scattering rates yjmp (cm-1). (b) calculated Hc2(0)-vi.-ylmp curve illustrating the transition from the clean to the dirty limit. Dotted line Hc2(0)-y,mp dependence in the dirty limit. (Drechsler et al. 2000 Fuchs... 

Fig. 43. (a and b) Resistivity versus temperature curves for HoNi2B2C and Yo.isHoo.8sNi2B2Ct respectively, showing reentrant behaviour, (c and d) The comparison with the neutron diffraction peak intensities shows that the a structure is strongly related to the reentrant behaviour, (e and f) Upper critical field determined from the resistive transitions shown in (a) and (b) (Eversmann et al. 1996 Milder et al. 1997 Kreyssig et al. 1997). 

Fig. 46. Temperature dependence of the upper critical field Hcj for TmNiil C and ErNi2B2C single crystals. Circles H a. triangles H c (after Canfield and Bud ko 2001).

Fig. 60. Concentration dependence of various properties of polycrystalline Y(Ni xPt )2B2C obtained by specific heat measurements transition temperature Tc exponent a and parameter Hc2 from eq. (6) upper critical field Hc2(0) at T =0, where the dotted line schematically describes the dirty limit corresponding to the isotropic single band case (in reality there is a finite intersection with the field-axis for the dotted asymptotic line, see Shulga and Drechsler 2002) exponent fi of eq. (8) for the curvature of the electronic specific heat in the mixed state and Sommerfeld constant xn (after Lipp et al. 2001).

Fig. 63. Temperature dependence of the upper critical field, HC2(T), (a) of YNi2B2C and Tby Yq 9Ni2B2C and (b) of Tby i Y0 8N12B2C single crystals for two directions of the applied magnetic field W (001) (closed squares) and //11[ 100] (open squares), alter Bitterlich et al. (2001).

Summary. On the basis of phenomenological Ginzburg-Landau approach we investigate the problem of order parameter nucleation in a ferromagnetic superconductor and hybrid superconductor - ferromagnetic (S/F) systems with a domain structure in an applied external magnetic field H. We study the interplay between the superconductivity localized at the domain walls and between the domain walls and show that such interplay determines a peculiar nonlinear temperature dependence of the upper critical field. For hybrid S/F systems we also study the possible oscillatory behavior of the critical temperature TC(H) similar to the Little-Parks effect. 

The goal of the present paper is to study the unusual nonlinear behavior of the temperature dependence of the upper critical field observed experimentally in hybrid S/F systems and ferromagnetic superconductors using the GL model. We consider a linearized GL equation which is equivalent to... 

The high critical temperature superconductors show a strong anisotropy in different properties critical current density [1], resistivity [2, 3] and the upper critical field [2],... 

Orzechowski K (1999) Electric field effect on the upper critical solution temperature. Chem Phys 240 275-281... 

In contrast to the conventional s-wave superconductor picture above, Gasparov et al. (2006) report unusual temperature dependence of the magnetic penetration depth A.(T) and upper critical field Hc2(T) and propose that ZrBi2 has an unconventional two-gap superconductivity. 

FIGURE 24 The temperature dependence of the upper critical field of an YNi2B2C thin film, resistively measured in the principal crystallographic directions (from Wimbush et al., 2004b). 

FIGURE 27 The temperature dependence of the upper critical field of YNi2B2C measured by susceptibility with applied field parallel to c at ambient pressure, 2.3, 3.3, 5.4,7.6, 9.0, and 11.7 GPa (from top to bottom). The solid lines correspond to two-band fits (after Suderow et al., 2004). 

TABLE 9 Experimental data for Lu(Nii xCox)2B2C (after Cheon et al., 1998) with Tc determined from electrical resistivity p(T), po—the residual resistivity, Hc2(0)—the zero-temperature upper critical field, l—the mean free path, and 0—the BCS coherence length... 

Fig. 2.10. Upper critical field, Bc2, vs temperature for the three principal crystal directions of (TMTSP)2C104. Prom [103]...

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