Mikhail Eremin

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The spin dynamics of the prototypical quasi-one-dimensional antiferromagnetic Heisenberg spin S=1/2 chain KCuF3 is investigated by electron spin resonance spectroscopy. Our analysis shows that the peculiarities of the spin dynamics require a new dynamical form of the antisymmetric anisotropic spin-spin interaction. This dynamical Dzyaloshinsky-Moriya(More)
We present a simple derivation of an expression for the superfluid density n(s) α 1/λ(2) in superconductors with the tight binding energy dispersion. The derived expression is discussed in detail because of its distinction from the known expressions for ordinary superconductors with parabolic energy dispersion. We apply this expression for the experimental(More)
Optical absorption spectra of Cr-Cr pair center in KZnF3:Cr ,Cr crystal were investigated in wide temperature range. Broad band at 30800 cm is attributed to cation-cation eg-electron transfer transition. Narrow lines with maxima at 16720 cm and 19880 cm have been assigned to purely electronic exchangeinduced electric-dipole transitions from the ground(More)
The spin-freezing process in underdoped cuprate superconductors, observed most by NMR-NQR relaxation and muon spin rotation and sometimes interpreted as coexistence of antiferromagnetic and superconducting states, is generally thought to result from randomly distributed magnetic moments related to charge inhomogeneities (possibly stripes) which exhibit(More)
The importance of magnetic inhomogeneities in understanding the complex phase diagrams of manganite systems like La1−xSrxMnO3 [1] becomes more and more evident, only to mention phase separation scenarios, chemical inhomogeneities or the recent description of the Colossal Magneto Resistance effect as a Griffith phase [2]. Electron Spin Resonance not only(More)
We report on optical measurements of the 1D Heisenberg antiferromagnet KCuF3. The crystal-field excitations of the Cu2+ ions have been observed and their temperature dependence can be understood in terms of magnetic and exchange-induced dipole mechanisms and vibronic interactions. Above TN we observe a new temperature scale TS characterized by the emergence(More)
We adopt a t1 − t2 − t3 −J −G model for explanation of x = 1/8 anomaly in La2−xSrxCuO4 family compound. The calculated charge susceptibility shows a maximum near (π, π) at intermediate temperatures and near (π, π/2) as temperature approaches zero, in agreement with neutron scattering experiments. Coulomb repulsion G between the first neighbors turns out to(More)
The strong line broadening observed in electron spin resonance on NaV2O5 is found to originate from an unusual type of the symmetric anisotropic exchange interaction with simultaneous spin-orbit coupling on both sites. The microscopically derived anisotropic exchange constant is almost 2 orders of magnitude larger than the one obtained from conventional(More)
A system of self-consistent integral equations for the superconducting gap is formulated and solved taking account of the instability of the normal phase of bilayered cuprates against charge-density waves. The critical parameters are calculated as a function of the wave vector, temperature, and doping index. It is found that the region in which(More)