Related papers: Spin canting and lattice symmetry in La$_2$CuO$_4$
We reinterpret neutron scattering and Raman spectroscopy experiments in La(2-x)Sr(x)CuO(4), showing modulation of spin and lattice degrees of freedom both in the low-temperature orthorhombic and tetragonal phases, in terms of a…
The magnetic anisotropy af a rectangular Cu-O-Cu bond is investigated in second order of the spin-orbit interaction. Such a bond is characteristic for cuprates having edge sharing CuO_2 chains, and exists also in the Cu_3O_4 plane or in…
A magnetic susceptibility which decreases with decreasing temperature is observed in all $CuO_2$ based superconductors with less than optimal doping. We propose that in $La_{2-x} Sr_x CuO_4$ this is due to antiferromagnetic ordering which…
The Cu spin magnetism in La2-x-yEuySrxCuO4 (x<=0.17; y<=0.2) has been studied by means of magnetization measurements up to 14 T. Our results clearly show that in the antiferromagnetic phase Dzyaloshinsky-Moriya (DM)superexchange causes Cu…
We study the spin-wave spectrum and the spin-flop transitions in La_2CuO_4 in a uniform magnetic field at zero temperature. Using the non-linear sigma-model, we show that a field applied along the orthorhombic b direction leads to a…
Correlated materials with competing spin-orbit and crystal-field interactions can host composite spin-orbital magnons that are highly susceptible to structural and electronic perturbations, enabling the control of magnetic dynamics beyond…
We use transport and neutron-scattering measurements to show that a magnetic-field-induced transition from noncollinear to collinear spin arrangement in adjacent CuO_{2} planes of lightly electron-doped Pr_{1.3-x}La_{0.7}Ce_{x}CuO_{4}…
We demonstrate that the onset of complex spin orders in ACr$_2$O$_4$ spinels with magnetic A$=$Co, Fe and Cu ions lowers the lattice symmetry. This is clearly indicated by the emergence of anisotropic lattice dynamics -- as evidenced by the…
New surprises continue to be revealed about La$_2$CuO$_4$, the parent compound of the original cuprate superconductor. Here we present neutron scattering evidence that the structural symmetry is lower than commonly assumed. The static…
The effects of quantum fluctuations on the magnetic field dependence of the spin-wave gaps in the lamellar antiferromagnet La$_2$CuO$_4$ are considered. Nonlinear corrections to the spin-wave spectrum are calculated to leading order in 1/S,…
Including the orbital off-diagonal spin and charge condensates in the self consistent determination of magnetic order within a realistic three-orbital model for the $4d^4$ compound $\rm Ca_2 Ru O_4$, reveals a host of novel features…
The magnetic excitations of the square-lattice spin-1/2 antiferromagnet and high-Tc parent La2CuO4 are determined using high-resolution inelastic neutron scattering. Sharp spin waves with absolute intensities in agreement with theory…
We have studied relationship between local lattice disorder, Ru 4$d$ spin-orbit interaction, and global spin/orbital orders of Ca$_{2-x}$Sr$_x$RuO$_4$ in the Sr-rich and Ca-rich regions of its phase diagram by using unrestricted…
To leading order in displacement size, the scattering of electrons in a Cu-O plane from O displacements perpendicular to that plane is due to spin-orbit coupling. This scattering is investigated with the following results: (1) As a…
The alloy Ca$_{2-x}$Sr$_x$RuO$_4$ exhibits a complex phase diagram with peculiar magnetic metallic phases. In this paper some aspects of this alloy are discussed based on a mean field theory for an effective Kugel-Khomskii model of…
We determined the magnetic structure of CuCr$_2$O$_4$ using neutron diffraction and irreducible representation analysis. The measurements identified a new phase between 155 K and 125 K as nearly collinear magnetic ordering in the Cr…
Phononic and magnetic Raman scattering are studied in La$_{2-x-y}$Nd$_{y}$Sr$_{x}$CuO$_{4}$ with three doping concentrations: x ~ 1/8, y = 0; x ~ 1/8, y = 0.4; and x = 0.01, y = 0. We observe strong disorder in the tilt pattern of the…
Spin-orbit entangled magnetic dipoles, often referred to as pseudospins, provide a new avenue to explore novel magnetism inconceivable in the weak spin-orbit coupling limit, but the nature of their low-energy interactions remains to be…
Systematic Raman studies on several cuprates (YBa$_{\rm 2}$Cu$_{\rm 3}$O$_{\rm x}$, YBa$_{\rm 2}$Cu$_{\rm 4}$O$_{\rm 8}$ or Bi$_{\rm 2}$Sr$_{\rm 2}$CaCu$_{\rm 2}$O$_{\rm 8}$) have shown that at optimal doping the compounds are at the edge…
The magnetic structure of (La${}_{1.8}$Eu${}_{0.2}$)CuO${}_4$ has been studied by magnetization measurements of single crystals, which show antiferromagnetic long-range order below $T_N$ = 265 K and a structural phase transition at $T_s$ =…