Diana V. Shopova

Fluctuation induced first order phase transition in thin films of type I superconductors

Abstract The effect of fluctuation induced weakly first order phase transition known for three-dimensional (3D) type I superconductors appears in a modified and strongly enhanced variant in thin (quasi-2D) superconducting films. The unusual thermodynamic properties of this new type of first order phase transitions and the possibility for an experimental verification of the effect are established and discussed.

Some basic aspects of quantum phase transitions

Several basic problems ofthe theory ofquantum phase transitions are reviewed. The e.ect ofthe quantum correlations on the phase transition properties is considered with the help ofbasic models ofstatistical physics. The e.ect ofquenched disorder on the quantum phase transitions is also discussed. The review is perf ormed within the f ramework ofthe thermodynamic scaling theory and by the most general methods ofstatistical physics for the treatment of phase transitions: general length-scale arguments, exact solutions, mean 3eld approximation, Hubbard–Stratonovich transformation, Feynman path integral approach, and renormalization group in the 3eld theoretical variant. Some new ideas and results are presented. Outstanding theoretical problems are mentioned. c

Correlations, Coherence, and Order

Structural Peculiarities in Fullerene Crystals V.L. Aksenov, V.S. Shakhmatov. Fundamental Problems of Quantum Critical Phenomena L. De Cesare, D.I. Uzunov. Critical Fluctuations in Normal-to-Superconducting Transition R. Folk, Yu. Holovatch. Spin Dynamics of Spin Polarized Fermi Liquids I.A. Fomin. Chaotic Vortices in He II as an Example of Highly Disordered State of One Dimensional Singularities S.K. Nemirovskii. Orientational Disorder and Order in C60-Fullerite and in MC60-Alkali Metal Fullerides A.V. Nikolaev, et al. Desorption Induced by Electronic Transitions: Application to Ionic Compounds M. Piacentini, N. Zema. Strong Electron Correlation Effects in Copper Oxides N.M. Plakida. Quantum Phase Transitions in 2d Quantum Liquids A.M.J. Schakel. List of Contributors. Index.

Thermodynamics of ferromagnetic superconductors with spin-triplet electron pairing

We present a general thermodynamic theory that describes phases and phase transitions of ferromagnetic superconductors with spin-triplet electron Cooper pairing. The theory is based on extended Ginzburg-Landau expansion in powers of superconducting and ferromagnetic order parameters. We propose a simple form for the dependence of theory parameters on the pressure that allows correct theoretical outline of the temperature-pressure phase diagram for which, at low temperatures, a stable phase of coexistence of

Meissner phases in spin-triplet ferromagnetic superconductors

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Phase diagram of a class of spin-triplet ferromagnetic superconductors

-wave superconductivity and itinerant ferromagnetism appears. We demonstrate that the theory is in agreement with the experimental data for some intermetallic compounds that are experimentally proven to be itinerant ferromagnetic exhibiting spin-triplet superconductivity. Some basic features of quantum phase transitions in such systems are explained and clarified. We propose to group the spin-triplet ferromagnetic superconductors in two different types of thermodynamic behavior, on the basis of quantitative criterion deduced from the present theory and the analysis of experimental data.

Phenomenological study of spin-triplet ferromagnetic superconductors

We present new results for the properties of phases and phase transitions in spin-triplet ferromagnetic superconductors. The superconductivity of the mixed phase of coexistence of ferromagnetism and unconventional superconductivity is triggered by the presence of spontaneous magnetization. The mixed phase is stable but the other superconducting phases that usually exist in unconventional superconductors are either unstable or for particular values of the parameters of the theory some of them are metastable at relatively low temperatures in a quite narrow domain of the phase diagram. Phase transitions from the normal phase to the phase of coexistence is of first order while the phase transition from the ferromagnetic phase to the coexistence phase can be either of first or second order depending on the concrete substance. Cooper pair and crystal anisotropies determine a more precise outline of the phase diagram shape and reduce the degeneration of ground states of the system but they do not change drastically phase stability domains and thermodynamic properties of the respective phases. The results are discussed in view of application to metallic ferromagnets as

On the phase diagrams of the ferromagnetic superconductors UGe2 and ZrZn2

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Dimensional crossover of the thermodynamic properties near the phase transition to superconducting state in type I superconductors

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Phase transitions to spin‐triplet ferromagnetic superconductivity in neutron stars

\mathrm{Zr}{\mathrm{Zn}}_{2}