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D. I. Uzunov

Publications and source records attributed to D. I. Uzunov.

12 recordsLinked to original sources
arXiv2013

Comment on "Fluctuation-induced first-order transition p-wave superconductors" by Qi Li, D. Belitz, and J. Toner [Phys. Rev. B79, 054514 (2009)]

In this Comment, we show that the paper by Qi Li, D. Belitz and J. Toner, published in Phys. Rev. B {\bf 79}, 054514 (2009), contains an incomplete mean-field analysis of a simple model of Ginzburg-Landau type. The latter contains a stable non-unitary phase, which has not been found in this study and is missing in the outlined picture of possible stable phases. In this Comment, the mean field analysis has been corrected, the errors have been explained in details and relevant topics have been discussed. Shortcomings in the mean-field-like and renormalization group studies in the mentioned paper have also been revealed.

cond-mat.supr-con↗
arXiv2007

Gauge effects on phase transitions in superconductors

Classic and recent results for gauge effects on the properties of the normal-to-superconducting phase transition in bulk and thin film superconductors are reviewed. Similar problems in the description of other natural systems (liquid crystals, quantum field theory, early universe) are also discussed. The relatively strong gauge effects on the fluctuations of the ordering field at low spatial dimensionality D and, in particular, in thin (quasi-2D) films are considered in details. A special attention is paid to the fluctuations of the gauge field. It is shown that the mechanism in which these gauge fluctuations affect on the order of the phase transition and other phase transition properties varies with the variation of the spatial dimensionality D. The problem for the experimental confirmation of the theoretical predictions about the order of the phase transitions in gauge systems is discussed.

cond-mat.supr-con↗
arXiv2005

Critical behaviour of thin films with quenched impurities

The critical behaviour of thin films containing quenched random impurities and inhomogeneities is investigated by the renormalization-group method. The finite-size crossover in impure films has been considered on the basis of the fundamental relationship between the effective spatial dimensionality and the characteristic lengths of the system. The difference between the critical properties of infinite systems and films is demonstrated and investigated. A new critical exponent, describing the scaling properties of the thickness of films with extended impurities has been deduced and calculated. A special attention is paid to the critical behaviour of real impure films.

cond-mat.stat-mech↗
arXiv2004

Phases and phase transitions in spin-triplet ferromagnetic superconductors

Recent results for the coexistence of ferromagnetism and unconventional superconductivity with spin-triplet Cooper pairing are reviewed on the basis of the quasi-phenomenological Ginzburg-Landau theory. New results are reported. The results are discussed in view of applications to metallic compounds as UGe2, URhGe, ZrZn2.

cond-mat.supr-con↗
arXiv2003

Homogeneous Phase of Coexistence of Spin-Triplet Superconductivity and Ferromagnetism

The coexistence of a homogeneous (Meissner-like) phase of spin-triplet superconductivity and ferromagnetism is investigated within the framework of a phenomenological model of spin-triplet ferromagnetic superconductors. The results are discussed in view of application to metallic ferromagnets as UGe$_2$, ZrZn$_2$, URhGe, and Fe.

cond-mat.supr-con↗
arXiv2003

Phase diagram of a class of spin-triplet ferromagnetic superconductors

We investigate thermodynamic phases, including the phase of coexistence of superconductivity and ferromagnetism, the possible phase transitions of first and second order, and the shape of the phase diagram in mean-field approximation for a phenomenological model of spin-triplet ferromagnetic superconductors. The results are discussed in view of application to metallic ferromagnets as UGe$_2$, ZrZn$_2$, URhGe, and Fe.

cond-mat.supr-con↗
arXiv2003

Some basic aspects of quantum phase transitions

Several basic problems of the theory of quantum phase transitions are reviewed. The effect of the quantum correlations on the phase transition properties is considered with the help of basic models of statistical physics. The effect of quenched disorder on the quantum phase transitions is also discussed. The review is performed within the framework of the thermodynamic scaling theory and by the most general methods of statistical physics for the treatment of phase transitions: general length-scale arguments, exact solutions, mean field approximation, Hubbard-Stratonovich transformation, Feynman path integral approach, and renormalization group in the field theoretical variant. Some new ideas and results are presented. Outstanding theoretical problems are mentioned.

cond-mat.stat-mech↗
arXiv2003

Thermodynamic properties of the phase transition to superconducting state in thin films of type I superconductors

The effect of magnetic fluctuations on the free energy, the order parameter profile and the latent heat at the equilibrium point of the first order phase transition to superconducting state in thin films of type I superconductors is considered. The possibility for an experimental observation of the fluctuation change of the order of the superconducting phase transition is briefly discussed. Numerical data for the order parameter jump and the latent heat of Al films are presented for needs of experimental studies.

cond-mat.supr-con↗
arXiv2001

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

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.

cond-mat.supr-con↗