Temperature evolution of crystal structure and magnetic glassy freezing in single layered Ruddlesden-Popper phase CaPrFe0.5Co0.5O4

Abstract

We report here the structural and magnetic properties of a magnetic glassy Ruddlesden-Popper single layer oxide, CaPrFe_0.5Co_0.5O₄. Structural characterization of CaPrFe_0.5Co_0.5O₄ using Synchrotron X-ray diffraction points to orthorhombic structure crystallizing in Bmab space group at room temperature. Temperature dependent synchrotron analysis indicates a structural anomaly at ∼200 K, which can be correlated to a plausible orthorhombic distortion due to strain within the Bmab space group. Furthermore, temperature dependent Raman spectra corroborate the presence of the structural anomaly observed at the same temperature. Our investigation of the ac and dc magnetization, along with the observed magnetic memory effect, demonstrates that the material enters a magnetic glassy phase at ∼25 K. This glassy behaviour arises due to competing magnetic exchange interactions resulting from the presence of randomly occupied Fe and Co ions with different valence states (Fe³⁺/Fe⁴⁺ and Co³⁺/Co²⁺), as confirmed by X-ray photoelectron spectroscopy. These interactions lead to the freezing of cluster spins, giving rise to the magnetic glassy state at low temperatures. Additionally, neutron diffraction analysis confirms the occurrence of magnetic glassy phase.