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Magnetoresistance and temperature coefficient of resistance (TCR) of manganites with ferromagnetism have been reported extensively, but the magnetoresistance and TCR of antiferromagnetic manganites are scarce. The transport properties, TCR, and magnetoresistance effect of antiferromagnetic NdMnO3 have been studied in this work. NdMnO3 samples exhibit semiconductor conductivity, and with the different applied magnetic fields, they still maintain semiconductor characteristics and have considerable stability. Under an applied magnetic field of 6 T, a small negative magnetoresistance of 8% appears near 150 K. Moreover, the conduction mechanism and TCR of NdMnO3 are studied. Three models, thermal activation (TA) model, small polaron (SP) model, and variable range jump (VRH) model, are used to analyze the electrical transport of NdMnO3 samples. The results show that the transport behavior of NdMnO3 samples is more consistent with the TA model. The maximum TCR is 9.4% K−1 within the low temperature region (above liquid nitrogen temperature). The TCR decreases with increasing temperature and it remains 2.5% K−1 near room temperature. Antiferromagnetic NdMnO3 has good TCR performance, which can be applied to temperature sensing field and has good application prospect in antiferromagnetic insulating electronic devices. [ABSTRACT FROM AUTHOR]

The structure, magnetic, transport and magnetoresistance properties of SrMnO3 sample have been investigated. The SrMnO3 sample has single-phase structure with hexagonal symmetry, which is obtained by the X-ray diffraction. The scanning electron microscope reveals the particles of the sample are evenly distributed. The composition of the SrMnO3 sample is detected using the energy dispersive spectrometer, indicating the element ratio of Sr:Mn:O = 19.25:20.35:60.40. The magnetic, electrical transport and the magnetoresistance effect are studied via the temperature dependences of the magnetization, the resistivity and the magnetoresistance. An antiferromagnetic phase transition near 300 K appears in the SrMnO3 sample, and no significant entropy change can be found in the antiferromagnetic sample. The sample shows the insulator state since the resistance increases gradually with the decrease of temperature. Therefore, SrMnO3 is an antiferromagnetic insulator material. Moreover, the resistivity reduces significantly with the applied magnetic field, indicating an existence of magnetoresistance. Remarkably, the room-temperature magnetoresistance of the antiferromagnetic insulator SrMnO3 reaches 16.68% under 60 kOe field. This work opens our understanding of magneto-transport and magnetic properties of the antiferromagnetic SrMnO3. The discovery of magnetoresistance near room temperature in the antiferromagnetic insulator (SrMnO3) is of great significance for the development of antiferromagnetic spintronics. [ABSTRACT FROM AUTHOR]