9.5 XPS and ZPS: Core Level Entrapment and Polarization
197
the atomic lattice of a material as they move. But when electrons join together
to become Cooer pairs, they undergo a remarkable transformation. Electrons by
themselves are fermions, particles that obey the Pauli exclusion principle, which
means each electron tends to keep its own quantum state. Cooer pairs, however, act
like bosons, which can happily share the same state. That bosonic behavior allows
Cooer pairs to coordinate their movements with other sets of Cooer pairs in a way
that reduces resistance to zero [84].
The high temperature cuprate superconductors, represent another extreme case
that superconductivity can be realized in the underdoped region where there is neither
well-defined Fermi surface due to the pseudogap formation nor quasiparticles near
the antinodal regions in the normal state. The superconductivity is realized in a system
with well-defined Fermi surface but without quasiparticles along the surface in the
normal state.
However, the HTSC and the effect of atomic undercoordination in the monolayer
and defect are beyond the description of the BCS theory.
One may consider first the elemental selectivity in the HTSC and TI substance.
The fact that some compounds of B, C, N, O, F and elements surrounding them,
particularly in group V and VI in the periodic table, form HTSC and TIs, albeit the
T C and the coherent energy, implies an underlying similarity in these elements. It
has been certain that N, O and F could generate nonbonding and antibonding states
near the Fermi surface upon their sp
3 -orbital hybridization. C and N can undergo
sp
2 -orbital hybridization as well with creation of the unpaired and paired electrons
[85]. In turn, these localized lone pairs and the associated antibonding electrons may
have a high chance of forming Copper pairs dominating the character of the HTSCs
and TIs. When an external electric field is applied, these localized pairs of electrons
are easily excited and hence become highly conducting, in a concerted fashion, given
suitable channels of transportation. Compared with the findings of graphene edge
Dirac Fermion states, the effective mass of these electrons is very small and their
group velocity is extremely high. An important characteristics is that these HTSCs
all assume a two-dimensional layered structure, such as “Cu
p :O
−2 :Cu
p :” chains or
CuO 2 planes, on which superconductivity relays.
As a plausible mechanism governing the HTSC and TI, the strong correlation of
electronic spins has attracted much attention. The presence of the nonbonding and
the antibonding states near Fermi surface should play at least a role of competence.
If the 1s electrons of B and C are excited to occupy the hybridized 2sp
3 orbits, B and
C would likely form valence band structures similar to those of N and O and hence
result in the superconductivity. Atoms of group V and VI elements should maintain
features of weak sp-orbital hybridization, and therefore, the nonbonding lone pairs
could be a factor of dominance in both HTSC and TI conductivities. The exposition
of the mechanism of HTSC from the perspective of antibond and nonbond formation
and the corresponding electronics and energetics would be an approach culminating
new knowledge. The spin-spin coupling may determine the coherent peak energy and
197
the atomic lattice of a material as they move. But when electrons join together
to become Cooer pairs, they undergo a remarkable transformation. Electrons by
themselves are fermions, particles that obey the Pauli exclusion principle, which
means each electron tends to keep its own quantum state. Cooer pairs, however, act
like bosons, which can happily share the same state. That bosonic behavior allows
Cooer pairs to coordinate their movements with other sets of Cooer pairs in a way
that reduces resistance to zero [84].
The high temperature cuprate superconductors, represent another extreme case
that superconductivity can be realized in the underdoped region where there is neither
well-defined Fermi surface due to the pseudogap formation nor quasiparticles near
the antinodal regions in the normal state. The superconductivity is realized in a system
with well-defined Fermi surface but without quasiparticles along the surface in the
normal state.
However, the HTSC and the effect of atomic undercoordination in the monolayer
and defect are beyond the description of the BCS theory.
One may consider first the elemental selectivity in the HTSC and TI substance.
The fact that some compounds of B, C, N, O, F and elements surrounding them,
particularly in group V and VI in the periodic table, form HTSC and TIs, albeit the
T C and the coherent energy, implies an underlying similarity in these elements. It
has been certain that N, O and F could generate nonbonding and antibonding states
near the Fermi surface upon their sp
3 -orbital hybridization. C and N can undergo
sp
2 -orbital hybridization as well with creation of the unpaired and paired electrons
[85]. In turn, these localized lone pairs and the associated antibonding electrons may
have a high chance of forming Copper pairs dominating the character of the HTSCs
and TIs. When an external electric field is applied, these localized pairs of electrons
are easily excited and hence become highly conducting, in a concerted fashion, given
suitable channels of transportation. Compared with the findings of graphene edge
Dirac Fermion states, the effective mass of these electrons is very small and their
group velocity is extremely high. An important characteristics is that these HTSCs
all assume a two-dimensional layered structure, such as “Cu
p :O
−2 :Cu
p :” chains or
CuO 2 planes, on which superconductivity relays.
As a plausible mechanism governing the HTSC and TI, the strong correlation of
electronic spins has attracted much attention. The presence of the nonbonding and
the antibonding states near Fermi surface should play at least a role of competence.
If the 1s electrons of B and C are excited to occupy the hybridized 2sp
3 orbits, B and
C would likely form valence band structures similar to those of N and O and hence
result in the superconductivity. Atoms of group V and VI elements should maintain
features of weak sp-orbital hybridization, and therefore, the nonbonding lone pairs
could be a factor of dominance in both HTSC and TI conductivities. The exposition
of the mechanism of HTSC from the perspective of antibond and nonbond formation
and the corresponding electronics and energetics would be an approach culminating
new knowledge. The spin-spin coupling may determine the coherent peak energy and