Magnetic frustration in a quantum spin chain: the case of linarite PbCuSO4(OH)2

• Published in: Physical review letters Vol. 108; no. 11; p. 117202
• Main Authors: Willenberg, B, Schäpers, M, Rule, K C, Süllow, S, Reehuis, M, Ryll, H, Klemke, B, Kiefer, K, Schottenhamel, W, Büchner, B, Ouladdiaf, B, Uhlarz, M, Beyer, R, Wosnitza, J, Wolter, A U B
• Format: Journal Article
• Language: English
• Published: United States 16.03.2012
• ISSN: 1079-7114

We present a combined neutron diffraction and bulk thermodynamic study of the natural mineral linarite PbCuSO4(OH)2, this way establishing the nature of the ground-state magnetic order. An incommensurate magnetic ordering with a propagation vector k=(0,0.186,1/2) was found below T(N)=2.8 K in a zero magnetic field. The analysis of the neutron diffraction data yields an elliptical helical structure, where one component (0.638μ(B)) is in the monoclinic ac plane forming an angle with the a axis of 27(2)°, while the other component (0.833μ(B)) points along the b 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.