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Probing the Pseudogap by Change in Chemical Potential

Top: Time-resolved ARPES spectrum. Bottom: Transient change of chemical potential for optimally doped (left) and slightly underdoped (right) Bi2212 as function of temperature. .

Scientific Achievement
Picosecond perturbation of chemical potential shows how the pseudogap (PG) state of cuprate superconductors inverts the density of states.

Significance and Impact
These results rule out one of the most accepted proposals that the PG phase is induced by fluctuating Cooper pairs, and prove its relation to a distinct order.

Research Details

  • An infrared laser pulse (1.5eV) excites Bi2212, a cuprate superconductor, and an ultraviolet pulse (6eV) measures the chemical potential by angle-resolved photoemission spectroscopy (ARPES).
  • Developped a new method to measure particle-hole symmetry.
  • Comparison of two samples with different size pseudogaps shows an inverted density of states.

T. L. Miller, W. T. Zhang, H. Eisaki, A. Lanzara. Phys. Rev. Lett. 118, 097001 (2017) DOI: 10.1103/PhysRevLett.118.097001