Abstract
We present a combined neutron diffraction and bulk thermodynamic study of the natural mineral linarite , this way establishing the nature of the ground-state magnetic order. An incommensurate magnetic ordering with a propagation vector was found below in a zero magnetic field. The analysis of the neutron diffraction data yields an elliptical helical structure, where one component () is in the monoclinic plane forming an angle with the axis of 27(2)°, while the other component () points along the axis. From a detailed thermodynamic study of bulk linarite in magnetic fields up to 12 T, applied along the chain direction, a very rich magnetic phase diagram is established, with multiple field-induced phases, and possibly short-range-order effects occurring in high fields. Our data establish linarite as a model compound of the frustrated one-dimensional spin chain, with ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor interactions. Long-range magnetic order is brought about by interchain coupling 1 order of magnitude smaller than the intrachain coupling.
- Received 17 November 2011
DOI:https://doi.org/10.1103/PhysRevLett.108.117202
© 2012 American Physical Society