Search

The 11 series of the iron chalcogenide has the simplest structure among all the iron-based superconductors, yet rather rich physical properties. In this way, the study on the 11 series has been one of the hottest topics in the iron-based superconductors. In this research, we have successfully synthesized Fe1-xNixS (x = 0, 0.01, 0.05, 0.1, 0.2) single crystals with P4/nmm using a hydrothermal method and self-flux method, and then studied their magnetic properties. Ni doping on FeS superconductor would suddenly suppress superconductivity. Meanwhile, it introduces a short-range antiferromagnetism and weak ferromagnetism, the coexistence of which induces an exchange bias. Our study further proves that superconductivity in 11 series is rather sensitive to the impurity on the Fe site, which is close to the short-range antiferromagnetism. Besides, their exchange bias would have potential application on information storage, spin valves, magnetic tunnel junction, etc. [ABSTRACT FROM AUTHOR]

A series of copper thiospinel compounds, CuCo2S4‐xSex (x = 0, 0.2, 0.4, 0.6, 0.8), have been successfully synthesized by solid‐state reaction and their structure and magnetic properties have been studied. The Rietveld refinements of X‐ray diffractions indicate that both the lattice constants and the nearest‐neighbor Cu‐Cu distances increase with increasing selenium doping. A weakly antiferromagnetic transition occurring at about 4 K is observed in CuCo2S4. Two antiferromagnetic transitions at about 3.5 K and 6 K are observed in selenium‐doped samples, which suggest that the exchange couplings associated with Cu‐S(Se)‐Cu and Cu‐Se(S)‐Cu, respectively, are responsible for the two antiferromagnetic transitions. Detailed analysis of the experimental results further indicates that the nearest‐neighbor molecular field coefficient is comparable to the next‐neighbor molecular field coefficient. We propose a reasonable model to explain this phenomenon. [ABSTRACT FROM AUTHOR]