Spin dynamics of the low-dimensional magnet (CH3)(2)NH2CuCl3

摘要

Dimethylammonium copper (II) chloride (also known as DMACuCl(3) or MCCL) is a low-dimensional S = (1)/(2) quantum spin system proposed to be an alternating ferro-antiferromagnetic chain with similar magnitude ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions. Subsequently, it was shown that the existing bulk measurements could be adequately modeled by considering DMACuCl(3) as independent AFM and FM dimer spin pairs. We present here new inelastic neutron scattering measurements of the spin excitations in single crystals of DMACuCl(3). These results show significant quasi-one-dimensional coupling, however the magnetic excitations do not propagate along the expected direction. We observe a band of excitations with a gap of Delta = 0.95 MeV and a bandwidth of 0.82 MeV. (c) 2006 Elsevier B.V. All rights reserved.