Observation of high-temperature magnetic transition and existence of ferromagnetic short-range correlations above transition in double perovskite La2FeMnO6

Abstract

We present the observation of a high-temperature magnetic transition along with ferromagnetic short-range correlations (FSCs) in La₂FeMnO₆ perovskite system. XPS analysis confirmed the presence of Fe³⁺ and Mn³⁺ cations. Magnetization vs. temperature curves show two distinct transitions at T_C1 ∼ 60 K and T_C ∼ 425 K. Coercivity values of ∼1140 Oe and ∼35 Oe are observed at 2 K and 300 K respectively. Thermomagnetic analysis reveals the presence of FSCs in La₂FeMnO₆ up to T* = 570 K, well above the transition point, similar to a Griffiths-like phase (GP). The presence of ferromagnetic clusters in the paramagnetic region might be due to the intrinsic inhomogeneities associated with the structure, the quenched disorder related to the B-site cations and the antisite boundaries. The coefficient of lower temperature electronic specific heat is as high as 59.5 mJ mol⁻¹ K⁻². The electron spin resonance spectra show ferromagnetic resonance signals that point to the possibility of the presence of FSCs at room temperature. The material seems to be quite a promising candidate for some room temperature applications due to the possibility of the coexistence of functionalities like ferromagnetism, ferrimagnetism, GP, magnetotransport coupling, etc. in a single material.