Evidence for field-induced quantum critical route to a Fermi liquid in overdoped Tl₂Ba₂CuO_6+x

We report an unanticipated transformation from a non-Fermi- to a Fermi-liquid state driven by magnetic field in a highly overdoped Tl 2Ba2CuOe+x with Tc ∼ 15 K. From the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid ρc ρc(0) + AT2 features, accompanied by a field-linear magnetoresistance, appear above a temperature-dependent field HFL, which decreases linearly with decreasing temperature and points to a quantum critical point near the upper critical field HC2(0). The observed field-induced quantum criticality with a power-law diverging A(H) bears a striking resemblance to that of heavy-fermion superconductor CeCoIn 5, suggesting a common underlying physics in these strongly correlated electron systems. © 2009 IOP Publishing Ltd.