Statics and dynamics of an incommensurate spin order in a geometrically frustrated antiferromagnet CdCr$_2$O$_4$

J. -H. Chung; M. Matsuda; S. -H. Lee; K. Kakurai; H. Ueda; T. J. Sato; H. Takagi; K. -P. Hong; S. Park

doi:10.1103/PhysRevLett.95.247204

paper

Statics and dynamics of an incommensurate spin order in a geometrically frustrated antiferromagnet CdCr $_{2}$ O $_{4}$

arXiv:cond-mat/0510363 · doi:10.1103/PhysRevLett.95.247204

Abstract

Using elastic and inelastic neutron scattering we show that a cubic spinel, CdCr $_{2}$ O $_{4}$ , undergoes an elongation along the c-axis ( $c > a = b$ ) at its spin-Peierls-like phase transition at $T_{N}$ = 7.8 K. The NÃ©el phase ( $T < T_{N}$ ) has an incommesurate spin structure with a characteristic wave vector \textbf{Q} $_{M}$ = (0, $I^´$ ,1) with $I^´ \sim$ 0.09 and with spins lying on the $a c$ -plane. This is in stark contrast to another well-known Cr-based spinel, ZnCr $_{2}$ O $_{4}$ , that undergoes a c-axis contraction and a commensurate spin order. The magnetic excitations of the incommensurate NÃ©el state has a weak anisotropy gap of 0.6 meV and it consists of at least three bands extending up to 5 meV.

PRL in press

Statics and dynamics of an incommensurate spin order in a geometrically frustrated antiferromagnet CdCr2​O4​

Abstract

Statics and dynamics of an incommensurate spin order in a geometrically frustrated antiferromagnet CdCr $_{2}$ O $_{4}$