pdf, 9 MiB - Infoscience - EPFL

4.4. RESULTS AND DISCUSSION 95
0.04
N=144
S
0.03
0.02
1/8
VMC Honeycomb
VMC square
Mean field
0.01
0
0 0.1 0.2 0.3 0.4
Hole doping δ
Figure 4.7: Superconducting order parameter of our best wavefunction versus
doping in the 144 site cluster (filled squares). For the same value of J, we show the
slave-boson mean-field results (small open squares) the d-wave superconducting
order parameter (open squares) with periodic boundary conditions along e x and
anti-periodic conditions along e y in a 100 site cluster.
imatively 0.15 t (this rise and the maximal value seem to be independent of the
J value) and decreases to zero again. For comparison, the gap is always zero in
the square lattice, and in the triangular lattice it is finite at any doping except
at half-filling.
The range and amplitude of the superconducting phase suggests that only
weak superconductivity is observed in the honeycomb lattice (see figure 4.7): the
maximal amplitude and the range of existence are four times smaller than the
ones of the d–wave pairing in the square lattice. The amplitudes in the triangular
lattice are twice as large in the hole doped (t