Giant Negative Temperature Coefficient of Resistance and Magnetotransport in Antiferromagnetic CaMnO3

Abstract

CaMnO₃, a perovskite manganite known for its antiferromagnetic (AFM) and other physical properties, has underexplored transport properties and temperature coefficient of resistance (TCR). We report exceptional charge transport phenomena in orthorhombic CaMnO₃, revealing a record negative temperature coefficient of resistance (TCR =  − 31.8% K⁻¹ at 21 K) for antiferromagnetic insulators. Magnetic characterization shows a Néel temperature (T_N) of 81.5 K. This magnetic transition govern distinct charge transport regimes, variable-range hopping (VRH) below T_N and small polaron (SP) conduction above T_N, demonstrating the existence of magnetic-electric coupling. Remarkably, the material exhibits field-independent TCR stability up to 6 T and significant magnetoresistance (MR =  − 17.5% at 22 K). These findings demonstrate CaMnO₃ potential for antiferromagnetic spintronic applications, particularly in magnetic sensors and spin-engineered thermal detection technologies in extreme environments.