Smooth Evolution in Hall Coefficient in the Overdoped Cuprate Tl2201

Our understanding of the microscopic origin of superconductivity in the cuprates is dependent on our knowledge of the normal state. Recently a sharp transition in the carrier density was proposed, close to optimal doping in YBa₂Cu₃O_6+δ and Nd-doped La_2-xSr_xCuO₄^1,2. This transition was argued to be tied to the Pseudogap endpoint p*.
Here we report a study of the high field Hall coefficient of the single-layer cuprate Tl₂Ba₂CuO_6+δ (Tl2201) which shows that n_H(0) evolves smoothly in the overdoped, so-called strange metal, phase of cuprates. No evidence for a Pseudogap has to date been reported in this material. This raises the question for a universality of the proposed link between the Pseudogap endpoint and the transition in carrier density, from p to 1+p, inferred from the Hall coefficient.
Rather the evolution of n_H seems to correlate with the emergence of the anomalous linear-in-T term in the in-plane resistivity. The presented data will shed new light on the evolution that the cuprates take from a Fermi liquid behavior to a strongly correlated, highly complex behavior in the underdoped side of the phase diagram.
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