Spin-glass behavior and pyroelectric anomalies in a new lithium-based oxide, Li3FeRuO5

Abstract

The results of dc and ac magnetization, heat capacity, ⁵⁷Fe Mössbauer spectroscopy, dielectric, pyroelectric current and isothermal magneto-capacitance measurements of a recently reported lithium-rich layered oxide, Li₃FeRuO₅, related to LiCoO₂-type (rhombohedral, space group Rm), are presented. The results reveal that the compound undergoes spin-glass freezing at 15 K. There is a peak around 34 K in pyroelectric data, which cannot be attributed to ferroelectricity, but to the phenomenon of thermally stimulated depolarization current. As revealed by magnetocapacitance data above and below the magnetic ordering temperature, magnetic and electric dipoles appear to be coupled, thereby offering evidence for magnetodielectric coupling.