We present a model describing the lattice distortion and incommensurate magnetic order in the spinel CdCr2O4, a good realization of the Heisenberg "pyrochlore" antiferromagnet. The magnetic frustration is relieved through the spin-Peierls distortion of the lattice involving a phonon doublet with odd parity. The distortion stablizes a collinear magnetic order with the propagation wavevector q=2\pi(0,0,1). The lack of inversion symmetry makes the crystal structure chiral. The handedness is transferred to magnetic order by the relativistic spin-orbit coupling: the collinear state is twisted into a long spiral with the spins in the ac plane and q shifted to 2\pi(0,\delta,1).
@article{arxiv.cond-mat/0606039,
title = {Broken parity and a chiral ground state in the frustrated magnet CdCr2O4},
author = {Gia-Wei Chern and C. J. Fennie and O. Tchernyshyov},
journal= {arXiv preprint arXiv:cond-mat/0606039},
year = {2007}
}
Comments
Incremental changes in response to referee reports