Incoherent strange metal sharply bounded by a critical doping in Bi2212

A sharp boundary in the cuprates Many physicists working on cuprate superconductors believe that the so-called strange metal phase in the cuprate phase diagram is associated with a quantum critical point. Within this picture, the quantum critical point gives rise to a V-shaped region in the doping-temperature phase diagram of the cuprates: the strange metal phase. Chen et al. used angle-resolved photoemission spectroscopy in the cuprate family Bi2212 to challenge this view. By taking comprehensive measurements as a function of doping and temperature—and making sure that the signal was not affected by environmental conditions—they found an incoherent strange metal phase that was sharply separated from a conventional phase by a temperature-independent vertical line in the phase diagram. Science , this issue p. 1099