Influence of lattice distortion on the Curie temperature and spin–phonon coupling in LaMn_0.5Co_0.5O₃

Abstract

Two distinct ferromagnetic phases of LaMn_0.5Co_0.5O₃ having monoclinic structure with distinct physical properties have been studied. The ferromagnetic ordering temperature T_c is found to be different for both the phases. The origin of such contrasting characteristics is assigned to the changes in the distance(s) and angle(s) between Mn–O–Co resulting from distortions observed from neutron diffraction studies. Investigations on the temperature dependent Raman spectroscopy provide evidence for such structural characteristics, which affects the exchange interaction. The difference in B-site ordering which is evident from the neutron diffraction is also responsible for the difference in T_c. Raman scattering suggests the presence of spin–phonon coupling for both the phases around the T_c. Electrical transport properties of both the phases have been investigated based on the lattice distortion.