Acoustic study of dynamical molecular-spin state without magnetic phase transition in spin-frustrated ZnFe2O4

作者:Watanabe Tadataka*; Takita Shota; Tomiyasu Keisuke; Kamazawa Kazuya
来源:Physical Review B, 2015, 92(17): 174420.
DOI:10.1103/PhysRevB.92.174420

摘要

Ultrasound velocity measurements were performed on a single crystal of spin-frustrated ferrite spinel ZnFe2O4 from 300 K down to 2 K. In this cubic crystal, all the symmetrically independent elastic moduli exhibit softening with a characteristic minimum with decreasing temperature below similar to 100 K. This elastic anomaly suggests a coupling between dynamical lattice deformations and molecular-spin excitations. In contrast, the elastic anomalies, normally driven by the magnetostructural phase transition and its precursor, are absent in ZnFe2O4, suggesting that the spin-lattice coupling cannot play a role in relieving frustration within this compound. The present study infers that, for ZnFe2O4, the dynamical molecular-spin state evolves at low temperatures without undergoing precursor spin-lattice fluctuations and spin-lattice ordering. It is expected that ZnFe2O4 provides the unique dynamical spin-lattice liquidlike system, where not only the spin molecules but also the cubic lattice fluctuate spatially and temporally.

  • 出版日期2015-11-24