Possible superconductivity from incoherent carriers in overdoped cuprates

There is now compelling evidence that the normal state of superconducting overdoped cuprates is a strange metal comprising two distinct charge sectors, one governed by coherent quasiparticle excitations, the other seemingly incoherent and characterized by non-quasiparticle (Planckian) dissipation. The zero-temperature superfluid density n_s(0) n s ( 0 ) of overdoped cuprates exhibits an anomalous depletion with increased hole doping p p , falling to zero at the edge of the superconducting dome. Over the same doping range, the effective zero-temperature Hall number n_{\rm H} (0) transitions from p p to 1 + p p . By taking into account the presence of these two charge sectors, we demonstrate that in the overdoped cuprates Tl _2 2 Ba _2 2 CuO _{6+\delta} 6 + δ and La _{2-x} 2 − x Sr _x x CuO _4 4 , the growth in n_s(0) n s ( 0 ) as p p is decreased from the overdoped side may be compensated by the loss of carriers in the coherent sector. Such a correspondence is contrary to expectations from conventional BCS theory and implies that superconductivity in overdoped cuprates emerges uniquely from the sector that exhibits incoherent transport in the normal state.