Memory effect and inverse thermal hysteresis in La0.87Mn0.98Fe0.02Ox

Abstract

We have investigated electrical transport and magnetization studies as a function of temperature, magnetic field, and time for polycrystalline La0.87Mn0.98Fe0.02Ox. The temperature dependence of resistivity exhibits a bifurcation in the zero-field cooled and field-cooled behavior below the paramagnetic to ferromagnetic transition temperature (Tc≈205 K). We observe an inverse thermal hysteresis in field-cooled resistivity in the temperature range of 85–200 K. Similar thermal hysteresis in the field-cooled magnetization is also observed. In consistence with the thermal hysteresis, the relaxation of magnetization exhibits the different magnetic characteristics in the heating and cooling cycles. The sample shows interesting memory effect in the relaxation of field-cooled resistivity. The magnetoresistance and magnetization studies suggest that the above unusual features are ascribed to the inhomogeneous structural phase separation in the case of minor Fe substitution.