Quantum Phase Transitions in the Cuprate Superconductor Bi 2 Sr 2 − x La x CuO 6 + δ

摘要: To elucidate a quantum phase transition (QPT) in ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2\ensuremath{-}x}{\mathrm{La}}_{x}{\mathrm{CuO}}_{6+\ensuremath{\delta}}$, we measure charge and heat transport properties at very low temperatures examine the following characteristics for wide range of doping: normal-state resistivity anisotropy under 58 T, temperature dependence in-plane thermal conductivity ${\ensuremath{\kappa}}_{ab}$, magnetic-field ${\ensuremath{\kappa}}_{ab}$. It turns out that all them show signatures QPT $1/8$ hole doping. Together with recent Hall measurements T signified existence optimum doping, present results indicate there are two QPTs superconducting doping regime this material.