Low-Temperature Dielectric Behavior Induced by Multiscale Cooperative Effects of CuCr₂O₄ under Bias Electric Fields

Transition metal oxides with spinel structures exhibit diverse physical properties due to their complex lattices and electronic configurations. Among them, CuCr2O4 (CCO) demonstrates magnetoelectric coexistence at low temperatures, arising from multiple synergistic mechanisms. The Jahn–Teller (JT) effect induced by the depolarization behavior of tetrahedrally coordinated Cu2+ ions, along with the interplay between JT distortion and spin–orbit coupling in Cr3+ ions, collectively leads to multiple phase transitions in CCO at low temperatures. However, investigations into its electrical polarization behavior remain limited, though extensive studies have focused on the magnetic properties at low temperatures. Research on the origin and evolution of low-temperature electrical polarization in CCO holds significant potential for advancing the understanding of polarization mechanisms in type-II multiferroic materials. In this work, high-quality polycrystalline CCO was prepared using the sol–gel method. The low-temperature polarization origins and evolution of CCO were systematically studied through combined microstructural characterization and polarization measurements. Furthermore, detailed analyses of the distinct polarization mechanisms in CCO across different temperature ranges were conducted by applying in situ electric fields. These findings establish important theoretical and experimental foundations for the design and development of high-performance CCO-based electronic devices.