Magnetic soft modes in the locally distorted triangular antiferromagnet alpha-CaCr2O4

Abstract

In this paper we explore the phase diagram and excitations of a distorted triangular lattice antiferromagnet. The unique two-dimensional distortion considered here is very different from the 'isosceles'-type distortion that has been extensively investigated. We show that it is able to stabilize a 120° spin structure for a large range of exchange interaction values, while new structures are found for extreme distortions. A physical realization of this model is α-CaCr2O4 which has 120° structure but lies very close to the phase boundary. This is verified by inelastic neutron scattering which reveals unusual roton-like minima at reciprocal space points different from those corresponding to the magnetic order.

5 pages, 3 figures and lots of spin-waves

References in corpus (5)

• Flat spin wave dispersion in a triangular antiferromagnet
• Critical behavior of the metallic triangular-lattice Heisenberg antiferromagnet PdCrO2
• Magnetic excitations in the geometric frustrated multiferroic CuCrO${}_2$
• Spin dynamics of frustrated easy-axis triangular antiferromagnet 2H-AgNiO2 explored by inelastic neutron scattering
• Helical magnetism and structural anomalies in triangular lattice α-SrCr2O4

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