Investigation of spin-phonon coupling and local magnetic properties in magnetoelectric Fe2TeO6

Spin-phonon coupling originated from spin-lattice correlation depends upon different exchange interactions in transition metal oxides containing 3d magnetic ions. Spin-lattice coupling can influence the coupling mechanism in magnetoelectric material. To understand the spin-lattice correlation in inverse trirutile Fe2TeO6 (FTO), magnetic properties and phonon spectra are studied. Signature of short-range magnetic correlation induced by 5/2-5/2 dimeric interaction and magnetic anomaly at 150 K is perceived apart from the familiar sharp transition (TN~210K) corresponding to long-range order by magnetization and heat capacity measurement. The magnetic transitions and the spin dynamics are further locally probed by muon spin resonance (μSR) measurement in both zero fields (ZF) and longitudinal field (LF) mode. Three dynamically distinct temperature regimes; (i) T >TN, (ii) TN>T>150 K, and (iii) T<150 K, are observed. A swift change in spin dynamics is realized at 150K by μSR, though previous studies suggest long-range antiferromagnetic order. The observation of renormalization of different Raman modes below 210K suggests the existence of spin-phonon coupling in the material. The coupling strength is quantified as in the range 0.1-1.2 cm-1 following the two-spin cluster approximation. We propose that the spin-phonon coupling is mediated by the Fe-O2-Fe interbilayer exchange play a significant role in ME coupling observed in the material.