Superconductivity in the orthorhombic phase of thermoelectric CsPbxBi4−xTe6 with 0.3≤x≤1.0

•Bulk superconductivity is discovered in the orthorhombic CsPbxBi4−xTe6 materials.•The superconducting transition in Cs0.96Pb0.22Bi3.80Te6.02 occurs at Tc=3.1 K.•Physical property measurements concerning the bulk superconductivity were present.•Structural modulation due to Pb-ordering was observed.

Experimental measurements clearly reveal the presence of bulk superconductivity in the CsPbxBi4−xTe6 (0.3≤x≤1.0) materials, i.e. the first member of the thermoelectric series of Cs[PbmBi3Te5+m], these materials have the layered orthorhombic structure containing infinite anionic [PbBi3Te6]− slabs separated with Cs+ cations. Temperature dependences of electrical resistivity, magnetic susceptibility, and specific heat have consistently demonstrated that the superconducting transition in Cs0.96Pb0.25Bi3.75Te6.04 occurs at Tc=3.1 K, with a superconducting volume fraction close to 100% at 1.8 K. Structural study using aberration-corrected STEM/TEM reveals a rich variety of microstructural phenomena in correlation with the Pb-ordering and chemical inhomogeneity. The superconducting material Cs0.96Pb0.25Bi3.75Te6.04 with the highest Tc shows a clear ordered structure with a modulation wave vector of q≈a*/2+c*/1.35 on the a–c plane. Our study evidently demonstrates that superconductivity deriving upon doping of narrow-gap semiconductor is a viable approach for exploration of novel superconductors.

Graphical abstractBulk superconductivity is discovered in the orthorhombic Cs0.96Pb0.22Bi3.80Te6.02 materials with the superconducting transition Tc=3.1 K. The compound shows a clear ordered structure with a modulation wave vector of q≈a*/2+c*/1.35 on the a–c plane.Figure optionsDownload full-size imageDownload as PowerPoint slide