Emergence of superconductivity in (NH3)yMxMoSe2 (M: Li, Na and K)

Abstract

We report syntheses of new superconducting metal-doped MoSe2 materials (MxMoSe2). The superconducting MxMoSe2 samples were prepared using a liquid NH3 technique, and can be represented as ‘(NH3)yMxMoSe2’. The Tcs of these materials were approximately 5.0 K, independent of x and the specific metal atom. X-ray diffraction patterns of (NH3)yNaxMoSe2 were recorded using polycrystalline powders. An increase in lattice constant c showed that the Na atom was intercalated between MoSe2 layers. The x-independence of c was observed in (NH3)yNaxMoSe2, indicating the formation of a stoichiometric compound in the entire x range, which is consistent with the x-independence of Tc. A metallic edge of the Fermi level was observed in the photoemission spectrum at 30 K, demonstrating its metallic character in the normal state. Doping of MoSe2 with Li and K also yielded superconductivity. Thus, MoSe2 is a promising material for designing new superconductors, as are other transition metal dichalcogenides.

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“…Due to its simple operation and signal amplification, HCR has aroused much attention for sensitive analyses, [20][21][22] but the use of HCR-based intracellular signal amplification has been rarely reported.…”

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“…Metal intercalation has been achieved using the liquid ammonia (NH 3 ) method. Therefore, the metal atoms are codoped together with NH 3 or an amide, i.e., the MoS 2 and MoSe 2 compounds can provide a good intercalation space for metal atoms and molecules [16]. As described above, this originates in the weak interaction between layers.…”

“…Pressure-driven superconductivity is also observed in WTe 2 [4], which exhibits a T c as high as 7 K at 16.8 GPa. Metal intercalation in MoS 2 and MoSe 2 yielded superconductivity with T c ∼ 4 − 7 K [14][15][16]. Metal intercalation has been achieved using the liquid ammonia (NH 3 ) method.…”

“…Transition-metal dichalcogenides (TMDs) are of great interest to physicists and chemists because they have recently produced new and exciting physics, as well as potentially useful materials for future electronics [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Pressure-driven superconductivity [4][5][6], large magnetoresistance [7], and a large Nernst effect [8] have been observed in some TMDs, and a possible Weyl semimetal [9] and a two-dimensional topological insulator [10] are also being discussed.…”

“…In addition, a technique of exfoliation available for graphene can easily be used on TMD compounds. The weak van der Waals interaction between layers in TMDs allows the intercalation of various elements and molecules [14][15][16], providing a fascinating platform for exploration in physics and materials science.…”