Origin of Strange Metallic Phase in Cuprate Superconductors

Abstract

The origin of strange metallic phase is shown to exist due to these two conditions-(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. The theory is also exploited to explain (i) the upward-and downward-shifts in the T -linear resistivity curves, and (ii) the spectral weight transfer observed in the soft X-ray absorption spectroscopic measurements of the La-Sr-Cu-O Mott insulator.

Supercurrent flow with large superconductor gap in cuprates: resurrection of phonon-mediated Cooper pairs

“…It is now straightforward to observe (see Fig. 1) that when nsc transforms into sc, i J nsc (20) and (22)). Alternatively, from Eqs.…”

“…In the early days of our investigation [21], we have discovered that the strange metallic phase in cuprates above T sc has an anomalous gap, which turned out to be a nontrivial energy-level spacing, ξ non triv = 0 [20]. It is nontrivial because the energy levels are degenerate (gapless) and yet, ξ non triv = 0, and therefore, ξ non triv determines the electron transition probability between different orthogonal and degenerate wavefunctions [20]. Our immediate aim now is to formally get ξ non triv on board or into Eq.…”

“…The existence of strange metallic phase in cuprates above T sc necessitates one to write |E k − E k+q | = ξ non triv = ξ and |E k − E k −q | = ξ following Ref. [20] where ξ = ξ if q = q . From here onwards, our notation for ξ non triv reverts to ξ for convenience because we focus only on cuprates.…”

“…[30] to address QPT Tsc in cuprates. In particular, we require ξ to be unequivocal in determining the reason why C v is discontinuous at T sc , as well as why We stress that the validity and correctness of ξ above T sc in cuprates are irrefutable [20,21], and we will not reproduce them here. Briefly though, ξ has been proven to give unambiguous microscopic explanations on the doping-dependent electrodynamics above T sc .…”

“…Within IET formalism, we can ignore ∆ BCS (T sc , t), and instead, one can construct the function, C v (T sc , t) non eqm (see Eqs. (20), (21) and (22)) to expose that the transition to superconducting phase is a continuous process, which is as it should be from quantum thermodynamics point of view [30]. This means that, our lack of knowledge on the function, ∆ BCS (T sc , t) does not imply that it does not exist, for the same reason we cannot assume C v (T sc , t) non eqm does not exist just because C v (T ) measurements do not indicate any continuous process at T sc [33].…”