Slow Magnetic Order-Order Transition in the Spin Chain Antiferromagnet Ca3Co2O6

Abstract

Using powder neutron diffraction we have discovered an unusual magnetic order-order transition in the Ising spin chain compound Ca3Co2O6. On lowering the temperature an antiferromagnetic phase with propagation vector k=(0.5,-0.5,1) emerges from a higher temperature spin density wave structure with k=(0, 0, 1.01). This transition occurs over an unprecedented time-scale of several hours and is never complete.

4 pages + 2 pages of supplementary information, to appear in Physical Review Letters