ESR Studies on Bi0.5Ca0.5Mn0.95TE0.05O3 (TE = V, Cu and Zn)

In this work, the effect of transition element (TE = V, Cu, and Zn) substitution at Mn site on the electron spin resonance (ESR) of Bi0.5Ca0.5MnO3 was explored. The temperature (T) dependent double integrated intensity (DI) and peak to peak linewidth provide the estimation of charge ordering (CO) temperature T-CO, long-range antiferromagnetic (AFM) onset temperature, T-O, ordering temperature, T-N, and the information about the magnetic interactions. The T-CO values are 317 K, 317 K, 321 K, and 311 K for undoped, V, Cu, and Zn doped samples, respectively. It is noticed that V doping sharpens the CO transition, whereas Cu and Zn doping smears the CO transition. The temperature dependent magnetization measurements support the ESR observations. In the temperature range T > T-CO, ferromagnetic (FM) correlations dominate. In the temperature range T-CO > T > T-O, the samples are in the paramagnetic (PM + CO) phase. The AFM interactions dominate in the doped samples in this temperature range. The orbital ordering (OO) sets in progressively with decreasing temperature leading to onset of long-range AFM ordering at similar to 200 K for undoped and in the range 190-170 K for doped samples. The present study shows the strong competition between FM and AFM correlations as a function of temperature and composition of the sample.