arXiv subjects
Publications and source records attributed to Tian De Cao.
A d-p pairing curve that is consistent with the pseudogap curve observed in experiments is found on a d-p model on phonon mechanism. On the discovery we suggest that there are two pseudogaps associated with the nearly localized d-p pairs and nearly free p-p pairs. The p-p pairs look like bosons and are responsible for superconductivities.
This work investigates the relation between superconductivity and correlations. A simple calculation shows that the appropriate spin-charge correlation is the key role to any superconductivity, and this calculation is consistent with the analyses of unusual properties of superconductors. (Note: the Tc of this model is not given clearly in this work, but we have advanced this mechanism to a t-x model which includes various superconductivities and magnetisms (please see arXiv:0707.3660 and following works).)
Since the cuprate materials behave many curious properties, the mechanism that causes high-temperature superconductivity in copper oxide materials (cuprates) has been a controversial topic. To explain these curious properties, we must look out the physics what these materials include. In this letter, it is presented that there are the basic physics (1)-(9) in solid materials. I divide all solid materials into four categories, explain some properties of them qualitatively, and suggest some ways to turn a solid material into a superconductor. Particularly, this letter discusses the differences between the p-type high-Tc cuprate superconductors, the n-type superconductor Nd2-xCexCuO4, the BCS-superconductor similar MgB2, and heavy Fermions superconductors.
The basic feature of the BCS theory is that pairing occurs between electrons in states with opposite momentum and opposite spins, e.g., between states (k) and (-k), in which the symbols of vectors are neglected, and later theories followed the BCS theory. However, since the center of mass for any pair is not always static, we must consider the pairing between states (k) and (-k+q). In this letter, we derive a set of self-consistent equations for the correlation functions associated with the pairs that have non-opposite momentums, in which we find some new results. This means that some physics associated with superconductors should be re-explained in futures.