Ryusuke Ikeda

Renormalized fluctuation theory of resistive transition in high-temperature superconductors under magnetic field

We attempt to explain the broad resistive transition observed in high-temperature superconductors under an applied magnetic field by a renormalized theory of the order parameter fluctuations using a model of superconductors with layered structures. The results are compared with single-crystal resistivity data. They are in good agreement, at least in the higher temperature side of the resistive transition, where the theory is expected to be valid.

THEORY OF BROAD RESISTIVE TRANSITION IN HIGH TEMPERATURE SUPERCONDUCTORS UNDER MAGNETIC FIELD

We further develop the theory of renormalized superconducting fluctuations in a strong field, taking account of layer structure in high temperature superconductors and renormalization of fluctuations of higher Landau levels, both of which we neglected in our previous works. Performing detailed comparisons with recent resistivity data for bulk single crystal samples of YBCO and BSCCO, we find that the resulting expressions of fluctuation conductivities quantitatively explain the broadening of resistive transition for both cases of the field perpendicular and parallel to current. In particular, the single expression for the case I ⊥ B can cover not only the broad transition region but also the flux flow region observed at lower temperature.

Effects of Pauli paramagnetism on the superconducting vortex phase diagram in strong fields

The Ginzburg-Landau functional and the resultant phase diagram of quasi-two-dimensional superconductors in strong fields perpendicular to the layers, where the Pauli paramagnetic depairing is not negligible, are examined in detail by assuming the weak coupling BCS model with a

QUANTUM SUPERCONDUCTING FLUCTUATIONS AND DISSIPATION IN VORTEX STATES

{d}_{{x}^{2}\ensuremath{-}{y}^{2}}

Renormalized Superconducting Fluctuations in Magnetic Field -Extrapolation to Lower Temperature-

-like pairing. It is found that the temperature at which the mean field (MF) transition at

Fluctuation Effect on Magnetization and Specific Heat in High Temperature Superconductors under Magnetic Field

{H}_{c2}

Superconducting Ordering in Vortex States of Clean Type II Superconductors with Pinnings

changes into a discontinuous one lies much above another temperature at which a line

Antiferromagnetic ordering induced by paramagnetic depairing in unconventional superconductors

{H}_{\mathrm{FFLO}}(T)

Angular dependence of resistive transition in strongly anisotropic superconductors under magnetic field

of transition to a helical vortex solid similar to a Fulde-Ferrell-Larkin-Ovchinnikov state may begin to appear. In addition to MF results, details of a real phase diagram near the

Pairing states of superfluid He 3 in uniaxially anisotropic aerogel

{H}_{c2}(T)