Hole superconductivity in MgB2: a high Tc cuprate without Cu

Abstract

The theory of hole superconductivity explains high temperature superconductivity in cuprates as driven by pairing of hole carriers in oxygen pπ orbitals in the highly negatively charged Cu − O planes. The pairing mechanism is hole undressing and is Coulomb-interaction driven. We propose that the planes of B atoms in M gB2 are akin to the Cu − O planes without Cu, and that the recently observed high temperature superconductivity in M gB2 arises similarly from undressing of hole carriers in the planar boron px,y orbitals in the negatively charged B − planes. Doping M gB2 with electrons and with holes should mirror the behavior of underdoped and overdoped high Tc cuprates respectively. We discuss possible ways to achieve higher transition temperatures in boron compounds based on this theory.

“Break-junction” technique in application to layered superconductors (Review Article)

“…Magnesium diboride, having a layered crystal structure and the highest critical temperature (in a stoichiometric state and under the normal pressure) for binary compounds T c ≈ 40 K [89], is in many ways similar to HTSC cuprates [36,37,120]. However, since the strong isotope effect of boron clearly points to the phonon nature of the pairing mechanism in MgB 2 [121] then for many researchers the desire to describe the superconductivity phenomenon in MgB 2 only using the strong electron-phonon interaction and the values of the characteristic ratio 2Δ/k B T c < 5, is especially attractive [122][123][124].…”

Synthesis and characterization of excess magnesium MgB2 superconductor under inert carbon environment

“…Besides, it is a BCS superconductor [4] having T c with in strong coupling BCS limit [5]. Any attempts to increase the superconducting transition temperature [6][7][8][9] have not achieved success yet [10][11][12], due to its typical phonon coupling mechanism [13][14][15][16][17][18]. But the other critical parameters like critical current density, and upper critical field can be enhanced remarkably by nano-particle doping [19][20][21][22][23][24][25][26].…”

Structural Arrangements and Bonding Analysis of MgB2C2

“…In MgB2, the incompletely filled bonding σ bands with predominantly boron px and py character give rise to nearly cylindrical, hole-like Fermi surfaces of 2D character around the Γ point, indicating that the transport properties are dominated by the hole carriers in the plane containing B atoms. 13 As the electronic band structures of both materials with a 2D hole-like Fermi surface are quite similar, the hole-doped MgB 2 C 2 is believed to be a good candidate for the occurrence of high-temperature superconductivity.…”