Electron-spin-resonance study of the one-dimensional magnet (NH4)2MnF5

Abstract

Electron-spin-resonance (ESR) experiments have been performed on the quasione-dimensional magnet (NH 4 ) 2 MnF 5 . The ESR spectrum consists of two components, an extremely broad signal and a weak but sharp resonance on top of the broad signal. The resonance field of the dominating broad signal is most probably shifted by strong non-diagonal terms of the dynamic susceptibility to g-values well below g = 2 and becomes undetectable upon the onset of strong one-dimensional correlations below T 60 K. We attribute these two signals to Mn 3+ ions of the chains (broad resonance, intrinsic response of the sample) and to defects (small resonance), respectively. The ESR spectra reflect the evolution from the paramagnetic state (T > 60 K) to one-dimensional magnetic behaviour (T 60 K). The results are discussed with respect to the local anisotropy of the Mn 3+ ions and comparison is made with the behaviour of other one-dimensional magnetic compounds.

Comparison of the Non‐linear Spin Dynamics in Antiferromagnetic Chain Compounds Na2MnF5 and (ND4)2MnF5

“…3 we present the relaxation rate versus inverse temperature for the 57 Fe doped compounds of the fluoromanganates(III) mentioned above. Additionally, we present measurements for SrMnF 5…”

“…The coordination around Mn III is very nearly axially symmetric (D 4h ). The EPR-spectra for a single crystal of (NH 4 ) 2 MnF 5 (space group Pnma, Z ϭ 4 ) were found to be nearly isotropic with signals at g values of g Ќ ϭ 2.002 and g ʈ ϭ 1.997 [4,5].…”