The Library
Manifolds of magnetic ordered states and excitations in the almost Heisenberg pyrochlore antiferromagnet MgCr2O4
Tools
(2018) Manifolds of magnetic ordered states and excitations in the almost Heisenberg pyrochlore antiferromagnet MgCr2O4. Physical Review B, 97 (13). 134430. doi:10.1103/PhysRevB.97.134430 ISSN 2469-9950.
|
PDF
WRAP-Manifolds-of-magnetic-ordered-states-Balakrishnan-2018.pdf - Published Version - Requires a PDF viewer. Download (3748Kb) | Preview |
Official URL: http://dx.doi.org/10.1103/PhysRevB.97.134430
Abstract
In spinels ACr2O4 (A=Mg, Zn), realization of the classical pyrochlore Heisenberg antiferromagnet model is complicated by a strong spin-lattice coupling: the extensive degeneracy of the ground state is lifted by a magneto-structural transition at TN = 12.5 K. We study the resulting low-temperature low-symmetry crystal structure by synchrotron x-ray diffraction. The consistent features of x-ray low-temperature patterns are explained by the tetragonal model of Ehrenberg et al. [Pow. Diff. 17, 230 (2002)], while other features depend on sample or cooling protocol. A complex, partially ordered magnetic state is studied by neutron diffraction and spherical neutron polarimetry. Multiple magnetic domains of configuration arms of the propagation vectors k1 = (1/2 1/2 0), k2 = (1 0 1/2 ) appear. The ordered moment reaches 1.94(3) μB/Cr3+ for k1 and 2.08(3) μB/Cr3+ for k2, if equal amount of the k1 and k2 phases is assumed. The magnetic arrangements have the dominant components along the [110] and [1−10] diagonals and a smaller c component.We use inelastic neutron scattering to investigate the spin excitations, which comprise a mixture of dispersive spin waves propagating from the magnetic Bragg peaks and resonance modes centered at equal energy steps of 4.5 meV.We interpret these as acoustic and optical spin wave branches, but show that the neutron scattering cross sections of transitions within a unit of two corner-sharing tetrahedra match the observed intensity distribution of the resonances. The distinctive fingerprint of clusterlike excitations in the optical spin wave branches suggests that propagating excitations are localized by the complex crystal structure and magnetic orders.
Item Type: | Journal Article | |||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Subjects: | Q Science > QC Physics | |||||||||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | |||||||||||||||
Library of Congress Subject Headings (LCSH): | Chromite -- Magnetic properties, Spinel group -- Magnetic properties, Antiferromagnetism, X-rays -- Diffraction | |||||||||||||||
Journal or Publication Title: | Physical Review B | |||||||||||||||
Publisher: | American Physical Society | |||||||||||||||
ISSN: | 2469-9950 | |||||||||||||||
Official Date: | 27 April 2018 | |||||||||||||||
Dates: |
|
|||||||||||||||
Volume: | 97 | |||||||||||||||
Number: | 13 | |||||||||||||||
Article Number: | 134430 | |||||||||||||||
DOI: | 10.1103/PhysRevB.97.134430 | |||||||||||||||
Status: | Peer Reviewed | |||||||||||||||
Publication Status: | Published | |||||||||||||||
Access rights to Published version: | Restricted or Subscription Access | |||||||||||||||
Copyright Holders: | American Physical Society | |||||||||||||||
Date of first compliant deposit: | 1 May 2018 | |||||||||||||||
Date of first compliant Open Access: | 1 May 2018 | |||||||||||||||
RIOXX Funder/Project Grant: |
|
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |
Downloads
Downloads per month over past year