Observation of Exchange Bias in Antiferromagnetic Cr(0.79)Se Due to the Coexistence of Itinerant Weak Ferromagnetism at Low Temperatures

[Image: see text] We report on the structural, electrical transport, and magnetic properties of antiferromagnetic transition-metal monochalcogenide Cr(0.79)Se. Different from the existing off-stoichiometric compositions, Cr(0.79)Se is found to be synthesized into the same NiAs-type hexagonal crystal structure as that of CrSe. Resistivity data suggest Cr(0.79)Se to be a Fermi-liquid-type metal at low temperatures, while at intermediate temperatures, the resistivity depends sublinearly on the temperature. Eventually, at elevated temperatures, the rate of change of resistivity rapidly decreases with increasing temperature. Magnetic measurements suggest a transition from the paramagnetic phase to an antiferromagnetic phase at a Néel temperature of 225 K. Further reduction of the sample temperature results in the coexistence of weak ferromagnetism along with the antiferromagnetic phase below 100 K. As a result, below 100 K, we identify a significant exchange bias due to the interaction between the ferro- and antiferromagnetic phases. In addition, from temperature-dependent X-ray diffraction measurements, we observe that the NiAs-type structure is stable up to as high as 600 °C.