1107.4585 (Andrew Das Arulsamy)
Andrew Das Arulsamy
The normal state metallic behavior above the superconducting transition temperature (T_sc) remains one of the least understood properties since its discovery in cuprates by Bednorz and Muller. Apart from the pseudogap (T^*) phenomenon above T_sc, there is this T-linear resistivity that was first recognized by Anderson as strange simply because it does not obey the low-temperature T^2 electron-electron scattering rate predicted by the Fermi liquid theory. Here, we prove that the strange metallic phase arises if (i) the electrons are strongly interacting such that there are no band and Mott-Hubbard gaps, and (ii) the electronic energy levels are crossed in such a way that there is an electronic energy gap between two energy levels associated to two different wave functions. We show that this new electronic energy gap is a generalized gap (\xi), in which, the band and the Mott-Hubbard gaps are special cases. Our proof follows the Green function formalism, the one-band Hubbard model, the ionization energy theory and the energy-level spacing renormalization group method. The theory is further exploited to give unambiguous and self-consistent explanations as to why and how doping gives rise to (i) an upward- or a downward-shift in the T-linear resistivity curve, and (ii) the spectral weight transfer observed in the soft X-ray absorption spectroscopic measurements for the La-Sr-Cu-O Mott insulator. We provide a logical proof for the existence of a finite-temperature quantum phase transition from a strange to a Fermi metal, which can be related to the proof derived by Parameswaran, Shankar and Sondhi. The existence of finite-temperature quantum phase transitions also imply that the Fermi gas (\xi \rightarrow 0) and Fermi liquid (\xi \rightarrow irrelevant constant) are special cases within the ionization energy theory.
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http://arxiv.org/abs/1107.4585
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