Three-dimensional Heisenberg critical phenomena in La0.6Bi0.1Sr0.3−xCaxMn0.9Cu0.1O3 manganites (x = 0 and 0.05)

Abstract

In this paper, our main objective is to study the effect of Ca doping on the critical properties of La0.6Bi0.1Sr0.3−xCaxMn0.9Cu0.1O3 (x = 0 and 0.05). The X-ray diffraction analysis reveal that both specimens are indexed in the rhombohedral structure with R–3c space group. As for the magnetic studies, a second-order ferromagnetic–paramagnetic (FM–PM) phase transition takes place around the transition temperature (TC). Based on different methods such as extrapolation of the Arrott curve, Kouvel-Fisher procedure and critical isothermal analysis depending on the data from magnetic investigations, the examination of the critical behavior was performed. The values of the deduced critical exponent (β, γ, δ) for both compounds proved to be close to those predicted by Heisenberg's 3D model, revealing an inhomogeneous magnetic exchange coupling at short distances. These critical exponents show a good agreement with their corresponding values proven by Widom's law of scale, as well as the theory of scale. Additionally, a typical soft FM behavior with a low coercive field was observed at 10 K according to the hysteresis loops. These outcomes make our compounds good candidates for memory devices and magnetic recording.