Two pseudogaps with different energy scales at the antinode of the high-temperature Bi2Sr2CuO6superconductor using angle-resolved photoemission spectroscopy

We performed high-resolution angle-resolved photoemission spectroscopy on single-layered cuprate Bi${}_{2}$Sr${}_{2}$CuO${}_{6}$ to clarify the origin of the pseudogap. By using various photon energies, we succeeded in directly observing two different pseudogaps with two different energy scales which coexist in the antinodal region: one reflects the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-wave pairing strength while the other has a larger energy scale suggesting an origin distinct from superconductivity. The observed two-pseudogap behavior provides a key to fully understanding the pseudogap phenomena in cuprates.