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Comment: Comments on the work of Schmidt et al, Europhys. Lett. 55, 105 (2001), cond-mat/0101228 (for the reply see cond-mat/0111581). To be published in Europhys. Lett
Comment: 4 pages, 4 figures, to be published in Phys. Rev. Lett
Motivated by the intriguing properties of magnetic molecular wheels at field-induced level crossings, we investigate the spin-Peierls instability of antiferromagnetic rings in a field by exact diagonalizations of a microscopic spin model coupled to the lattice via a distortion-dependent Dzyaloshinskii-Moriya interaction. We show that, beyond the unconditional instability at level crossings for infinitesimal magnetoelastic coupling, the model is characterized by a stronger tendency to distort at higher level crossings and by a dramatic angular dependence with very sharp torque anomalies when the field is almost in the plane of the ring. These predictions are shown to compare remarkably well with available torque and nuclear magnetic resonance data on CsFe8.
We present a detailed analysis of the magnetic properties of two Cu(II) coordination compounds with the tetrazole-1-acetate ligand (t1a), previously reported in literature by Yu et al. [Q. Yu, X. Zhang, H. Bian, H. Liang, B. Zhao, S. Yan, D. Liao, Cryst. Growth Des. 8 (2008) 1140] and simultaneously synthesised independently by ourselves. We focus on methods of describing the susceptibility and magnetisation of a ferromagnetically-coupled S = 1/2 square network (2) and a tetranuclear S = 1/2 'butterfly' cluster (4) as well as discussion of the energy levels of such a cluster.
We have synthesized a new one-dimensional coordination polymer, [CuII(HL)2(4,4′-bpy)]n·2nH2O (1), (HL– = monodeprotonated 3-nitrophthalic acid, 4,4′-bpy = 4,4′-bipyridine) consisting of infinite chains of [CuII(HL)2(4,4′-bpy)]n and have investigated its structure and magnetic properties. Compound 1 crystallizes in the monoclinic C2/c space group with the [CuII(HL)2(4,4′-bpy)]n chains running parallel to the b axis. The chains are linked together by hydrogen bonding between the HL– groups and water molecules to form the three-dimensional crystal structure. The magnetic susceptibility of 1 can be well described using an antiferromagnetic S = 1/2 chain model with g = 2.11(1) and 2J = –0.61(1) cm–1. Several techniques for describing the susceptibility of S =1/2 chains are examined to compare their validity at lowvalues of kT/|2J|, includin...
We report on the synthesis, crystal structure and magnetic characterisation of the trinuclear, fluoride-bridged, molecular nanomagnet [Dy(hfac)(3)(H2O)-CrF2(py)(4)-Dy(hfac)(3)(NO3)] (1) (hfacH = 1,1,1,5,5,5-hexafluoroacetylacetone, py = pyridine) and a closely related dinuclear species [Dy(hfac)(4)-CrF2( py)(4)]center dot 1/2 CHCl3 (2). Element-specific magnetisation curves obtained on 1 by X-ray magnetic circular dichroism (XMCD) allow us to directly observe the field-induced transition from a ferrimagnetic to a ferromagnetic arrangement of the Dy and Cr magnetic moments. By fitting a spin-Hamiltonian model to the XMCD data we extract a weak antiferromagnetic exchange coupling of j -0.18 cm(-1) between the Dy-III and Cr-III ions. The value found from XMCD is consistent with SQUID magnetometry and inelastic neutron scattering measureme...
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