Charge-ordering breakdown dynamics and ferromagnetic resonance studies of B-site Cu diluted Pr1‒x Sr x MnO3

Abstract

Here, we report the influence of Jahn–Teller active Cu substitution on the charge-ordering (CO) characteristics of one of the well-known manganite Pr0.45Sr0.55MnO3 (S55) with a distorted tetragonal structure. Magnetization studies unveil a complex magnetic phase diagram for S55, showing distinct temperature ranges corresponding to various magnetic phases: a ferromagnetic phase dominated by the Double Exchange interaction with T C ∼ 220.5 K, an antiferromagnetic phase below T N ∼ 207.6 K induced by CO with a transition temperature of T CO ∼ 210 K consistent with the specific heat C P(T) data, and a mixed phase in the range T N < T < T CO due to the competitive interplay of these two interactions. Dilute substitution of Cu at the Mn B-sites disrupts the robust charge-ordered state, leading to enhanced ferrimagnetic order with T FN ∼273 K and significant magnetocrystalline anisotropy as confirmed by ferromagnetic resonance (FMR) studies. The Cu-substituted system displays a distinct cationic distribution compared to the pristine S55, contributing to its diverse magnetic structure. Our findings also reveal the irreversible metamagnetic transition (H T-Max ∼ 8.85 kOe at 180 K) associated with the CO phenomena in S55 and the first-order nature of the phase transition across T CO. The magnetic heat capacity critical analysis (C Mag = A (T − T N)−α ) yields the exponent, α = 0.097 (0.154) in the region T > T N (T < T N) consistent with the magnetic structure. The temperature dependence of FMR resonance field ΔH Res(T), peak-to-peak width H PP(T), and Gilbert damping factor α G(T) show clear anomalies across the magnetic transitions signifying the important role of admixtured (3+/4+) electronic state of Mn. Additionally, a strong correlation between the FMR α G(T) and switchable magnetic entropy change (ΔS Max ∼ −8/+ 3 J kg−1 K−1 for ΔH = 90 kOe) has also been established in S55.