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Broken parity and a chiral ground state in the frustrated magnet CdCr2O4

Gia-Wei Chern·C. J. Fennie·O. Tchernyshyov
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Abstract

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=2π(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 2π(0,δ,1).

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Gia-Wei Chern, C. J. Fennie, O. Tchernyshyov. 2006-07-21. Broken parity and a chiral ground state in the frustrated magnet CdCr2O4. https://doi.org/10.1103/physrevb.74.060405

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