Scanning Tunneling Microscope

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© Wikimedia Commons, CC Share Alike 2.5 Generic License. Author: Royce Hunt, 5 March 2007. Right: K. McElroy, D.-H. Lee, J. E. Hoffman, K. M. Lang, J. Lee, E.W. Hudson, H. Eisaki, S. Uchida, and J. C. Davis.

Not only are the energy gaps measured in this STM measurement remarkably inhomogenous, but their magnitude is seen to change markedly as the doping level and Tc are decreased. Results such as these have convinced many physicists that the average energy gap seen most clearly here, whose magnitude increases as the doping level decreases, is associated with the localization of quasiparticles in the pseudogap state, since it does not track the superconducting transition temperature as would be expected for pair condensation into a BCS superconducting pairing state. (Unit: 8)