Abstract
A B-site disordered double perovskite was successfully synthesized by the conventional sol-gel method. Detailed experimental analyses revealed that crystallizes in the orthorhombic space group, in which and ions are randomly distributed at the BB′ sites, and and ions are respectively ordered at the A and A′ sites in an alternating arrangement along the direction. has a semimetallic-to-semiconducting transition nature, and a paramagnetic-ferromagnetic (FM) second-order phase transition originating from the complex hybridization between Co and O states is also found to occur at K. Then the spin coupling between and randomly distributed on the B and B′ sites leads to a FM cluster spin-glass behavior with characteristic parameters of K, , and s. Additionally, Griffiths-like phase behavior was observed in the region , with K, consistent with the power law exponent of . The maximum isothermal magnetic entropy change and relative cooling power under a field of 40 kOe also indicate a magnetocaloric coupling wherein fitted critical exponents , and are far from any conventional universality class. Density functional theory calculations demonstrated spin short- and long-range ordering competitions for Fe/Co at BB′ sites, which arise predominantly from the stronger negatively charged ligand interaction with Co orbitals and the weakest Fe orbitals. This unconventional behavior is expected to be the main reason for the experimentally observed magnetic exchange distance decreasing with .
5 More- Received 16 April 2022
- Revised 2 October 2022
- Accepted 3 October 2022
DOI:https://doi.org/10.1103/PhysRevB.106.134439
©2022 American Physical Society