Acoustic study of dynamical molecular-spin state without magnetic phase transition in spin-frustrated ZnFe 2 O 4

摘要: Ultrasound velocity measurements were performed on a single crystal of spin-frustrated ferrite spinel ${\mathrm{ZnFe}}_{2}{\mathrm{O}}_{4}$ from 300 K down to 2 K. In this cubic crystal, all the symmetrically independent elastic moduli exhibit softening with characteristic minimum decreasing temperature below $\ensuremath{\sim}100$ This anomaly suggests coupling between dynamical lattice deformations and molecular-spin excitations. contrast, anomalies, normally driven by magnetostructural phase transition its precursor, are absent in ${\mathrm{ZnFe}}_{2}{\mathrm{O}}_{4}$, suggesting that spin-lattice cannot play role relieving frustration within compound. The present study infers that, for state evolves at low temperatures without undergoing precursor fluctuations ordering. It is expected provides unique liquidlike system, where not only spin molecules but also fluctuate spatially temporally.