Related papers: Why only hole conductors can be superconductors
The importance of electron-hole interband interactions is widely acknowledged for iron-pnictide superconductors with high transition temperatures (Tc). However, high-Tc superconductivity without hole carriers has been suggested in FeSe…
In paper III of this series (arXiv:0901.3612) we proposed a scenario of superconductivity driven by hole "undressing" that involved a complete redistribution of the occupation of single particle energy levels: the holes near the top of the…
I argue that the conventional BCS-London theory of superconductivity does not explain the most fundamental property of superconductors, the Meissner effect: how is the Meissner current generated, and how is it able to defy Faraday's law?…
Superconductivity occurs in systems that have a lot of negative charge: the highly negatively charged $(CuO2)^{--}$ planes in the cuprates, negatively charged $(FeAs)^-$ planes in the iron arsenides, and negatively charged $B^-$ planes in…
A review of the phenomenology and microscopy of cuprate superconductors is presented, with particular attention to universal conductance features, which reveal the existence of two electronic subsystems. The overall electronic system…
The underlying mechanism of unconventional high-temperature superconductivity is a great challenge to condensed matter physics. However, zero dissipation of electric current is the commonness of superconductors whether they are conventional…
In recent work, we discussed the difference between electrons and holes in energy band in solids from a many-particle point of view, originating in the electron-electron interaction, and argued that it has fundamental consequences for…
Superconductivity at temperatures up to 190 K at high pressures has recently been observed in $H_2S$ and interpreted as conventional BCS-electron-phonon-driven superconductivity.\cite{h2s} Instead we propose that it is another example of…
We propose that the superconductivity recently observed in Nd$_{0.8}$Sr$_{0.2}$NiO$_2$ with critical temperature in the range $9$ K to $15$ K results from the same charge carriers and the same mechanism that we have proposed give rise to…
A type I superconductor expels a magnetic field from its interior to a surface layer of thickness $\lambda_L$, the London penetration depth. $\lambda_L$ is a function of temperature, becoming smaller as the temperature decreases. Here we…
After three decades of enormous scientific inquiry, the emergence of superconductivity in the cuprates remains an unsolved puzzle. One major challenge has been to arrive at a satisfactory understanding of the unusual metallic normal state…
The newly discovered superconductivity in MgCNi3, though with Tc<8 K lower than that of the celebrated MgB2, is probably even more interesting in its many puzzling physical properties. MgCNi3 has been theoretically speculated to be unstable…
The origin of magnetism and superconductivity in iron-based superconductors is still unclear. Here, by investigating the momentum-dependent particle-hole excitations which quantify the tendency of itinerant electrons towards various…
A theory of the normal and superconducting states of piezomagnetic metals, which are altermagnetic materials, has been developed. This has been done in comparison with the corresponding theoretical description for metals that do not have…
A superconductor is a material that conducts electric current with no resistance. Superconductivity and magnetism are known to be antagonistic phenomena: superconductors expel weak external magnetic field (the Meissner effect) while a…
Is superconductivity associated with a lowering or an increase of the kinetic energy of the charge carriers? Conventional BCS theory predicts that the kinetic energy of carriers increases in the transition from the normal to the…
When a magnetic field is applied to a ferromagnetic body it starts to spin (Einstein-de Haas effect). This demonstrates the intimate connection between the electron's magnetic moment $\mu_B=e\hbar/2m_ec$, associated with its spin angular…
Superconductivity is a remarkably widespread phenomenon observed in most metals cooled down to very low temperatures. The ubiquity of such conventional superconductors, and the wide range of associated critical temperatures, is readily…
Self-assembling organic polymers and copper-oxide compounds are two classes of "strange" superconductors, whose challenging behavior does not comply with the traditional picture of Bardeen, Cooper, and Schrieffer (BCS) superconductivity in…
Recent development in the physics of high-temperature cuprate superconductivity is reviewed, with special emphasis on the phenomena of unconventional and non-universal low-energy excitations of hole- and electron-type cuprate…