Fig. 7: Intercalation effects on superconductivity and CDW.

a Temperature dependence of magnetic susceptibility χ for Li, K, Rb, Cs, and Ca intercalation for BP. Shown are ZFC (solid symbols) and FC (open symbols) measurements for an in-plane magnetic field of 10 Oe. The inset shows how T_c was determined for individual samples: it is defined as the sharp change in dχ/dT. b Magnetization M as a function of the magnetic field for intercalated compounds⁶⁰. c Crystal structure of Cu intercalated Bi₂Se₃ that makes superconducting Cu_xBi₂Se₃ (left), and random substitution of Cu by replacing Bi atoms making Bi_2-xCu_xSe₃ which is not superconductive (right).¹⁸⁷ d magnetic transport measurements of Cu_0.12Bi₂Se₃, which shows a superconducting transition at 3.8 K. Upper inset: superconductivity occurs only in a narrow window of x in Cu_xBi₂Se₃. Superconductivity is not found for x < 0.1 and x > 0.3, or in Bi_2-xCu_xSe₃. Lower inset: temperature dependence of the superconducting upper critical field of Cu_0.12Bi₂Se₃ for the magnetic field applied parallel to the c axis and parallel to the ab plane.¹⁸⁸. e Resistivity profile of single crystal Cu_0.12Bi₂Se₃ with applied current in ab-plane. The lower inset shows that the superconducting transition occurs at ̴ 3.8 K. The upper inset shows the magnetoresistance plot at T = 1.8 K. The second inset shows the zoomed in version of the resistivity plot and the third inset shows the comparison of the Seebeck coefficients of Cu_xBi₂Se₃ and Bi_2-xCu_xSe₃.¹⁸⁸ f Superconductivity in K intercalated 2H-MoS₂. g Superconducting phases of K intercalated 2H-MoS₂ at various K concentration⁵⁹. Electronic phase diagram of Cu intercalated TaS₂ and TiSe₂. Temperature (T) vs concentration (x) electronic phase diagram of Cu intercalated h TaS₂¹⁹⁰ and i TiSe₂ with inset showing the crystal structure¹⁹¹. Panels a, b reprinted with permission from Springer Nature Publications Nature Communications⁶⁰, Copyright (2017), advance online publication 23 February 2017 (https://doi.org/10.1038/ncomms15036, Nature Commun). Panel c reused with permission from John Wiley and Sons/Wang et al.¹⁸⁷. Panels d, e reused with permission from American Physical Society/Hor et al.¹⁸⁸ (https://doi.org/10.1103/PhysRevLett.104.057001); panels f, g adapted with permission from⁵⁹ Nano Lett. 16, 629–636. Copyright (2016). American Chemical Society; panel h reused with permission from American Physical Society/Wagner et al.¹⁹⁰ (https://doi.org/10.1103/PhysRevB.78.104520); panel i reprinted with permission from Springer Nature Publications Nat. Physics¹⁹¹, Copyright (2006), advance online publication 28 June 2006 (https://doi.org/10.1038/nphys360, Nat. Phys).