Muon spin rotation in the molecular-based layer ferrimagnets AFe(II)Fe(III)(C 2O 4) 3 (A=N( n-C 4H 9) 4, P(C 6H 5) 4)

Abstract

Zero field muon spin rotation was measured in polycrystalline samples of two molecular-based layer ferrimagnets AFe(II)Fe(III)(C 2O 4) 3 with A=N( n-C 4H 9) 4 and P(C 6H 5) 4 which, although having the same honeycomb layer structure, show, respectively, negative and positive low field magnetisation at low temperature. The time dependence of the muon decay asymmetry, measured between 100 and 4.5 K, is modelled best by a combination of fast Gaussian and slow Lorentzian functions. Sharp falls in the asymmetry at 44 K (N( n-C 4H 9) 4) and 38 K (P(C 6H 5) 4) are identified with the transition to long-range magnetic order.