Resonant x-ray scattering study of magnetic and orbital order inKCuF3

Abstract

We present the results of resonant x-ray scattering experiments on KCuF 3 . Structurally forbidden reflections, corresponding to magnetic and 3d-orbital long-range order, have been observed. Integrated intensities have been measured as a function of incident energy, polarization, azimuthal angle, and temperature. By means of ab initio local spin density approximation ͑LSDA͒ and local spin density approximation with on-site Coulomb interaction ͑LSDAϩU͒ calculations we determine the electronic structure of KCuF 3 and obtain the resonant x-ray scattering spectrum at the Cu K edge, which shows good agreement with the experimental data. Orbital and spin degrees of freedom are strongly coupled, and the temperature dependence of the intensity of orbital Bragg peaks reveals a correlation between magnetic and orbital order parameters.

Phononic and magnetic excitations in the quasi-one-dimensional Heisenberg antiferromagnet KCuF3

“…It is known that the ordered moment per Cu site in KCuF 3 is reduced by 50% at T << T N compared to the saturation value in 3D due to quantum fluctuations [25]. Therefore, this system clearly has aspects of both 1D and 3D spin-1/2 magnetism at low temperatures.…”

“…Details on crystal growth are described in Ref. 25. The sample has previously been investigated by ESR and optical spectroscopy [26,27].…”

“…Although orthorhombic distortions are involved for explaining the electron spin resonance (ESR) properties of KCuF 3 [19], discrepancies remain for the analysis of recent NQR [20], AFM resonance [21], and further experimental and theoretical findings [22,23]. Besides, in x-ray resonant scattering [24,25] of the OO in KCuF 3 indications for a coupling of lattice and magnetic degrees of freedom above T N are found. Only recently, the ESR properties for T > T N could be successfully explained within the tetragonal symmetry by assuming a dynamical Dzyaloshinsky-Moriya (DM) interaction related to strong oscillations of the bridging F -ions perpendicular to the crystallographic c axis [26].…”

KCrF3: Electronic structure and magnetic and orbital ordering from first principles

“…[10][11][12][13][14][15][16][17] Along the c axis, the orbital ordering pattern in KCrF 3 is rotated by 90°in consecutive layers. This in contrast to the manganite where the ordering along the c axis is a uniform repetition of the in-plane orbital structure.…”

Longitudinal magnetic dynamics and dimensional crossover in the quasi-one-dimensional spin-12Heisenberg antiferromagnetKCuF3Lake1, Tennant2, Nagler3 2005Phys. Rev. B5711600View full textAdd to dashboardCite

“…The Cu d orbitals are ordered, and there has been considerable work investigating this aspect of the structure, see e.g. [20]. A large orbital overlap through the fluorine p-orbital results in strong antiferromagnetic superexchange interactions (J=34 meV) coupling nearest neighbor magnetic sites in the c direction.…”