Interplay of Externally Doped and Thermally Activated Holes in La2-xSrxCuO4 and Their Impact on the Pseudogap Crossover

We presented the recent Hall effect data for a number of carriers in La_2-xSr_xCuO₄ as the sum of two components: the temperature independent term n₀(x), which is due to external doping, and the thermally activated contribution. Their balance determines the crossover temperature T^*(x) from the marginal Fermi liquid to pseudogap regime. The activation energy Δ(x) for thermally excited carriers equals the energy between the Fermi surface “arc” and the band bottom, as seen in angle-resolved photoemission spectroscopy experiments. Other implications for the (T, x)-phase diagram of cuprates are also discussed.