High pressure effects on non-fluorinated BiS2-based superconductors La${}_{1-x}$M${}_x$OBiS${}_2$ (M = Ti and Th)

Abstract

Layered \textit{Ln}OBiS${}_2$ compounds with \textit{Ln} = La, Ce, Pr, Nd, and Yb can be rendered conducting and superconducting via two routes, substitution of F for O or the tetravalent ions Ti, Zr, Hf, and Th for trivalent \textit{Ln} ions. Electrical resistivity measurements on non-fluorinated La${}_{0.80}$Ti${}_{0.20}$OBiS${}_2$ and La${}_{0.85}$Th${}_{0.15}$OBiS${}_2$ superconductors were performed between $\sim$1.5 K and 300 K and under pressure up to 2.4 GPa. For both compounds, the superconducting transition temperature $T_c$, which is $\sim$2.9 K at ambient pressure, gradually increases with pressure to 3.2-3.7 K at $\sim$1 GPa, above which it is suppressed and the superconducting transitions become very broad. Measurements of the normal state electrical resistivity of the two compounds reveal discontinuous changes of the resistivity as a function of pressure at $\sim$0.6 GPa. Surprisingly, above 1.3 GPa, semiconducting-like behavior reappears in La${}_{0.80}$Ti${}_{0.20}$OBiS${}_2$. This study reveals a new high-pressure phase of La${}_{1-x}$$M$${}_x$OBiS${}_2$ containing the tetravalent ions $M$ = Ti, Th which does not favor superconductivity. In contrast, application of pressure to fluorinated LaO${}_0.5$F${}_0.5$BiS${}_2$ produces an abrupt tetragonal-monoclinic transition to a metallic phase with an enhanced $T_c$. These results demonstrate that the response of the normal and superconducting properties of LaOBiS${}_2$-based compounds depends strongly on the atomic site where the electron donor ions are substituted.

References in corpus (19)

• Novel BiS2-based layered superconductor Bi4O4S3
• Superconductivity of F-substituted LnOBiS2 (Ln = La, Ce, Pr, Nd, Yb) compounds
• Superconductivity induced by La doping in Sr1-xLaxFBiS2 system
• Superconductivity induced by electron doping in the system La1-xMxOBiS2 (M = Ti, Zr, Hf, Th)
• Pressure-induced Enhancement of Superconductivity in BiS${}_2$-layered LaO${}_{1-x}$F${}_x$BiS${}_2$
• Charge-density wave, superconductivity and $f$-electron valence instability in EuBiS${}_2$F
• Anomalous Eu Valence State and Superconductivity in Undoped Eu3Bi2S4F4
• Enhancement of superconductivity near the pressure-induced semiconductor-metal transition in BiS2-based compounds LnO(0.5)F(0.5)BiS2 (Ln = La, Ce, Pr, Nd)
• Appearance of bulk Superconductivity under Hydrostatic Pressure in Sr0.5RE0.5FBiS2 (RE = Ce, Nd, Pr and Sm) compounds
• Impact of hydrostatic pressure on superconductivity of Sr0.5La0.5FBiS2
• First single crystal growth and structural analysis of superconducting layered bismuth oxyselenide; La(O,F)BiSe2
• Superconductivity and its Enhancement under High Pressure in "F-free" Single Crystals of CeOBiS${}_2$
• Effect of yttrium substitution on the superconducting properties of the system La${}_{1-\text{x}}$Y${}_{\text{x}}$O${}_{0.5}$F${}_{0.5}$BiS${}_2$
• Enhancement of Superconductivity in La${}_{1-x}$Sm${}_x$O${}_{0.5}$F${}_{0.5}$BiS${}_2$
• Pressure-Induced Phase Transition in La${}_{1-x}$Sm${}_x$O${}_{0.5}$F${}_{0.5}$BiS${}_2$
• Pressure-induced phase transition for single crystalline LaO0.5F0.5BiSe2
• Upper critical magnetic field of $Ln$O${}_{0.5}$F${}_{0.5}$BiS${}_2$ ($Ln$ = La, Nd) superconductors at ambient and high pressure
• Evidence for two distinct superconducting phases in EuBiS${}_2$F under pressure
• Observation of spin-orbit insulator-like behavior in LaOBiS${}_{2-x}$F${}_x$ (0.05 $\le$ $x$ $\le$ 0.2)

Cited by in corpus (3)

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