Probing magnetic order and disorder in the one-dimensional molecular spin chains CuF2(pyz) and [Ln(hfac)3(boaDTDA)]n (Ln=Sm, La) using implanted muons [dataset]

We present the results of muon-spin relaxation (μSR) measurements on antiferromagnetic and ferromagnetic spin chains. In antiferromagnetic CuF2(pyz) we identify a transition to long range magnetic order taking place at TN=0.6(1) K, allowing us to estimate a ratio with the intrachain exchange of TN/|J|=0.1 and the ratio of interchain to intrachain exchange coupling as |J/J|=0.05. The ferromagnetic chain [Sm(hfac)3(boaDTDA)]n undergoes an ordering transition at Tc=2.8(1) K, seen via a broad freezing of dynamic fluctuations on the muon (microsecond) timescale and implying Tc/|J|=0.6. The ordered radical moment continues to fluctuate on this timescale down to 0.3 K, while the Sm moments remain disordered. In contrast, the radical spins in [La(hfac)3(boaDTDA)]n remain magnetically disordered down to T=0.1 K suggesting Tc/|J|<0.17.