Time filter

Source Type

Mineev V.P.,CNRS Statistical Physics, Magnetism and Superconductivity
Journal of the Physical Society of Japan

The interplay of the microscopic models and the symmetry considerations in application to the superconducting state of putative chiral superconductor Sr 2RuO 4 are presented. There is demonstrated that chiral two-band superconducting ordering recently proposed as candidate for the superconducting state in this material and having the long-expected property such as the intrinsic Hall effect does not exist as energetically disadvantageous in comparison with the states not supporting the Hall effect. Other chiral multi-band superconducting states with intraband pairing do not support an intrinsic Hall properties as well. The superconducting states with direct interband pairing could serve as the probable candidates for the Hall effect existence. © 2012 The Physical Society of Japan. Source

Zhitomirsky M.E.,CNRS Statistical Physics, Magnetism and Superconductivity | Chernyshev A.L.,University of California at Irvine
Reviews of Modern Physics

A theoretical overview of the phenomenon of spontaneous magnon decays in quantum antiferromagnets is presented. The intrinsic zero-temperature damping of magnons in quantum spin systems is a fascinating many-body effect, which has recently attracted significant attention in view of its possible observation in neutron-scattering experiments. An introduction to the theory of magnon interactions and a discussion of necessary symmetry and kinematic conditions for spontaneous decays are provided. Various parallels with the decays of anharmonic phonons and excitations in superfluid He4 are extensively used. Three principal cases of spontaneous magnon decays are considered: field-induced decays in Heisenberg antiferromagnets, zero-field decays in spiral antiferromagnets, and triplon decays in quantum-disordered magnets. Analytical results are compared with available numerical data and prospective materials for experimental observation of the decay-related effects are briefly discussed. © 2013 American Physical Society. Source

Zhitomirsky M.E.,CNRS Statistical Physics, Magnetism and Superconductivity
Journal of Physics: Conference Series

We present a unified approach to the problem of degeneracy lifting in geometrically frustrated magnets with and without an external field. The method treats fluctuations around a classical spin configuration in terms of a real-space perturbation expansion. We calculate two lowest-order contributions for the Heisenberg spin Hamiltonian and use them to study the magnetization processes of spin-S triangular and kagomé antiferromagnets. Source

Maryasin V.S.,University Grenoble Alps | Zhitomirsky M.E.,CNRS Statistical Physics, Magnetism and Superconductivity
Physical Review B - Condensed Matter and Materials Physics

The effect of structural disorder is investigated for an XY pyrochlore antiferromagnet with continuous degeneracy of classical ground states. Two types of disorder - vacancies and weakly fluctuating exchange bonds - lift degeneracy, selecting the same subset of classical ground states. Analytic and numerical results demonstrate that such an "order by structural disorder" mechanism competes with the effect of thermal and quantum fluctuations. Our theory predicts that a small amount of nonmagnetic impurities in Er2Ti2O7 will stabilize the coplanar ψ3 (mx2-y2) magnetic structure as opposed to the ψ2 (m3z2-r2) state found in pure material. © 2014 American Physical Society. Source

Zhitomirsky M.E.,CNRS Statistical Physics, Magnetism and Superconductivity | Holdsworth P.C.W.,Ecole Normale Superieure de Lyon | Moessner R.,Max Planck Institute For Physik Komplexer Systeme
Physical Review B - Condensed Matter and Materials Physics

We study the finite-temperature transition in a model XY antiferromagnet on a pyrochlore lattice, which describes the pyrochlore material Er2Ti2O7. The ordered magnetic structure selected by thermal fluctuations is sixfold degenerate. Nevertheless, our classical Monte Carlo simulations show that the critical behavior corresponds to the three-dimensional XY universality class. We determine an additional critical exponent ν6=0.75>ν characteristic of a dangerously irrelevant scaling variable. Persistent thermal fluctuations in the ordered phase are revealed in Monte Carlo simulations by the peculiar coexistence of Bragg peaks and diffuse magnetic scattering, the feature also observed in neutron diffraction experiments. © 2014 American Physical Society. Source

Discover hidden collaborations