We present a set of layered materials that, unlike transition metal dichalcogenides, are built of square metal lattices leading to new functional properties such as superconductivity and ferromagnetism. Superconductivity has been known in the transition metal dichalcogenides such as TaS2 since the 1970’s and has been recently studied in the iron-based selenides. Just last year, it was proposed that the critical temperature Tc of FeSe can be increased from 8 K to 100 K when grown as a single layer on an SrTiO3 substrate. Our group’s strategy has been to incorporate layers such as metal hydroxides to understand superconductivity in (AOH)FeCh materials where A is an alkali metal and Ch = S2- and Se2-. Due to the weak van der Waals interactions that hold the chalcogenide layers together, the intercalation chemistry can lead to new phases with interesting superconducting properties. Furthermore, we have used our hydrothermal synthetic techniques to extend it to the sulfide family including the simple FeS in the tetragonal structure (i.e. mackinawite). We will present our work on the synthesis, characterization, and structural studies via neutron scattering of these materials, including our efforts to look beyond iron.

Layered transition metal chalcogenides based on square lattices as functional materials

253rd National Meeting (2017)

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