Spin freezing and dynamics in Ca_{3}Co_{2-x}Mn_{x}O_{6} (x ~ 0.95) investigated with implanted muons: disorder in the anisotropic next-nearest neighbor Ising model

TL;DR

This study uses muon-spin relaxation to explore spin dynamics and disorder in Ca_{3}Co_{2-x}Mn_{x}O_{6} (x~0.95), revealing persistent fluctuations and spin freezing phenomena at low temperatures.

Contribution

It provides new insights into the spin dynamics and disorder effects in this Ising chain magnet using implanted muons, connecting experimental results with the anisotropic next-nearest-neighbor Ising model.

Findings

Persistent spin fluctuations down to 1.6 K

A subtle dynamic change at ~18 K linked to spin clusters

Spin freezing below ~8 K for a minority of spins

Abstract

We present a muon-spin relaxation investigation of the Ising chain magnet Ca_{3}Co_{2-x}Mn_{x}O_{6} (x~0.95). We find dynamic spin fluctuations persisting down to the lowest measured temperature of 1.6 K. The previously observed transition at around T ~18 K is interpreted as a subtle change in dynamics for a minority of the spins coupling to the muon that we interpret as spins locking into clusters. The dynamics of this fraction of spins freeze below a temperature T_{SF}~8 K, while a majority of spins continue to fluctuate. An explanation of the low temperature behavior is suggested in terms of the predictions of the anisotropic next-nearest-neighbor Ising model.