Synthesis, structure, and physical properties of bilayer molybdate Sr₃Mo₂O₇ with flat-band

ABSTRACT

Bilayer molybdate Sr${}_3$Mo${}_2$O${}_7$ has been successfully synthesized by a modified solid-state reaction method. Magnetization measurements show that the compound is a paramagnetic material with a weak spin-glass state below about 4.5 K. Fitting to the magnetic susceptibility under a high magnetic field based on the Currie–Weiss law yields a magnetic moment of about 1.61 ${\mu }_B$ per Mo atom. The temperature dependence of resistivity exhibits a metallic behaviour in wide temperature region from 20 K to 300 K, but a slight upturn of resistivity with the behaviour of $\rho \propto -\ln (T)$ is observed at temperatures below about 20 K. Negative magneto-resistance behaviour has also been observed in the temperature region with resistivity upturning. Both effects indicate that a Kondo-like scattering occurs in the material. Resistivity measurements under high pressures up to 33.7 GPa are carried out, no superconductivity above 2 K has been observed, which is in contradiction to the theoretical prediction. We argue that the absence of superconductivity maybe because the flat-band is still too far away from the Fermi energy.

KEYWORDS:

• Sr${}_3$Mo${}_2$O${}_7$
• polycrystalline
• transition metal oxides
• magnetism
• transport properties
• high-pressure effects

Acknowledgments

This work was supported by the National Key R&D Program of China (grant numbers 2016YFA0300401 and 2016YFA0401704), the National Natural Science Foundation of China (grant numbers A0402/11534005 and A0402/11674164), and the Strategic Priority Research Program of Chinese Academy of Sciences (grant number XDB25000000).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Key R&D Program of China (grant numbers 2016YFA0300401 and 2016YFA0401704), the National Natural Science Foundation of China (grant numbers A0402/11534005 and A0402/11674164), and the Strategic Priority Research Program of Chinese Academy of Sciences (grant number XDB25000000).