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We present a combined experimental and theoretical analysis of the quasi-one-dimensional s = ½ Heisenberg
magnet linarite PbCuSO4(OH)2, with competing ferromagnetic nearest-neighbor and antiferromagnetic next-nearestneighbor
exchange interactions. It includes magnetization M(H), ESR and NMR studies as well as theoretical simulations of
the magnetic susceptibility and M(H)-data using the DMRG technique for quasi-1D isotropic spin models and a corresponding
analysis within the L(S)DA+U approach for the determination of the leading exchange couplings. As a result we arrive at new
values for these exchange interactions, which are surprisingly about an order of magnitude higher as determined previously.
[1] Furthermore, a manifold of field-induced phases are probed in the magnetization measurements, in particular along the chain direction. Via susceptibility and NMR investigations, we find characteristic features for the different magnetic phases and draw a preliminary phase diagram of linarite. Notably, a qualitative different dependence of 1/T1(T) in fields below and above 6.5 T seems to be an intriguing feature, whose origin is not clear yet, but which might be related to a magnetic quadrupolar spin liquid phase transition as recently predicted. [2] [1] M. Baran, et al., Phys. Stat. Sol. (c) 3, 220 (2006). [2] M. Sato, T. Momoi, A. Furusaki, Phys. Rev. B 79, 060406(R) (2009). |
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