Frequency effects on charge ordering in Y_0.5Ca_0.5MnO₃ by impedance spectroscopy

In this work, structural and electrical properties of Y_0.5Ca_0.5MnO₃ are investigated by employing X-ray diffraction and impedance spectroscopy, respectively. Applied ac electric field showed the charge ordering transition temperature around 265 K and below this temperature the heteromorphic behavior of the sample is discussed in the proximity of T_CO. With frequency effects the volume of robust charge orbital ordering (COO) domains diminishes due to different competing phases along with Jahn Teller distortions. Comprehensive melting and collapse of charge orbital ordering occurs below T_N(125 K), where a colossal drop in the value of impedance is observed. The change in profile of modulus plane plots determines the spreading of relaxation time of intermingled phases. Hopping mechanism is elaborated in terms of strong electron phonon coupling. Variable range hopping model and Arrhenius model are used to discuss the short and long range hopping between Mn³⁺ and Mn⁴⁺ channels assessing the activation energy E_a. - Highlights: • Present study contains a detailed investigation over the electrical and structural properties of Y_0.5Ca_0.5MnO₃ especially its behavior across the charge ordering transition. • Impedance measurements illustrate the comprehensive melting and collapse of robust charge orbital ordering with colossal drop in impedance. • In T_NCO, Coulomb interactions give rise to Jahn–Teller distortions badly frustrating the spins of manganese. • Modulus plane plots determine the spreading of relaxation time of intermingled phases indicating the contribution of grain boundary and grain interior. • Variable range hopping model and Arrhenius model are used to discuss the short and long range hopping between Mn³⁺ and Mn⁴⁺ channels assessing the activation energy E_a