title: Magnetic frustration in a quantum spin chain: the case of linarite PbCuSO4(OH)2.
abstract: 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.
authors.affiliation: Helmholtz Center Berlin for Materials and Energy, Berlin, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Willenberg
authors.forename: M
authors.initials: M
authors.lastname: Schäpers
authors.forename: K C
authors.initials: KC
authors.lastname: Rule
authors.forename: S
authors.initials: S
authors.lastname: Süllow
authors.forename: M
authors.initials: M
authors.lastname: Reehuis
authors.forename: H
authors.initials: H
authors.lastname: Ryll
authors.forename: B
authors.initials: B
authors.lastname: Klemke
authors.forename: K
authors.initials: K
authors.lastname: Kiefer
authors.forename: W
authors.initials: W
authors.lastname: Schottenhamel
authors.forename: B
authors.initials: B
authors.lastname: Büchner
authors.forename: B
authors.initials: B
authors.lastname: Ouladdiaf
authors.forename: M
authors.initials: M
authors.lastname: Uhlarz
authors.forename: R
authors.initials: R
authors.lastname: Beyer
authors.forename: J
authors.initials: J
authors.lastname: Wosnitza
authors.forename: A U B
authors.initials: AU
authors.lastname: Wolter