Muon-spin relaxation studies of the low-dimensional molecular compounds Mn(dca) 2(pyz) and Fe(NCS) 2(pyz) 2

Abstract

We present the results of zero field muon-spin relaxation ( μ + SR) studies of the molecular magnets Mn(dca) 2(pyz) and Fe(NCS) 2(pyz) 2 (where dca = [ N ( CN ) 2 ] - and pyz = pyrazine ). Both of these materials possess low-dimensional structural motifs resulting in magnetic behaviour consistent with this reduced dimensionality. Mn(dca) 2(pyz) is formed from Mn–pyz–Mn chains, linked with dca anions to form two interpenetrating three-dimensional (3D) networks. Antiferromagnetic ordering in this compound is seen as a rapid change in the measured asymmetry around T N = 2.5 K . Fe(NCS) 2(pyz) 2 is a two-dimensional (2D) sheet-like polymer with the sheets consisting of Fe atoms bridged by pyz ligands. μ + SR measurements display both the 3D and 2D nature of the material in the measured relaxation spectra. We observe the transition into the LRO state below T N along with an excitation of E = 1.09 ( 5 ) meV above T N associated with fluctuations within the correlated 2D layers.