SciPost Phys. 6, 018 (2019) ·
published 5 February 2019

· pdf
Shortrange antiferromagnetic correlations are known to open a spin gap in
the repulsive Hubbard model on ladders with $M$ legs, when $M$ is even. We show
that the spin gap originates from the formation of correlated pairs of
electrons with opposite spin, captured by the hidden ordering of a spinparity
operator. Since both spin gap and parity vanish in the twodimensional limit,
we introduce the fractional generalization of spin parity and prove that it
remains finite in the thermodynamic limit. Our results are based upon
variational wave functions and Monte Carlo calculations: performing a finite
sizescaling analysis with growing $M$, we show that the doping region where
the parity is finite coincides with the range in which superconductivity is
observed in two spatial dimensions. Our observations support the idea that
superconductivity emerges out of spin gapped phases on ladders, driven by a
spinpairing mechanism, in which the ordering is conveniently captured by the
finiteness of the fractional spinparity operator.
Submissions
Submissions for which this Contributor is identified as an author:
Dr Tocchio: "We thank the Referee for recog..."
in Report on Superconductivity in the Hubbard model: a hiddenorder diagnostics from the LutherEmery phase on ladders