1,268 research outputs found
Emergence of flat bands and their impact on superconductivity of MoSiP
The first-principles calculations and measurements of the magnetic
penetration depths, the upper critical field, and the specific heat were
performed for a family of MoSiP superconducotrs.
First-principles calculations suggest the presence of a flat band dispersion,
which gradually shifts to the Fermi level as a function of phosphorus doping
. The flat band approaches the Fermi level at , thus separating
MoSiP between the purely steep band and the steep band/flat
band superconducting regimes. The emergence of flat bands lead to an abrupt
change of nearly all the superconducting quantities. In particular, a strong
reduction of the coherence length and enhancement of the penetration
depth result in nearly factor of three increase of the
Ginzburg-Landau parameter (from for
to for ) thus initiating the
transition of MoSiP from a moderate to an extreme type-II
superconductivity.Comment: 6 pages, 4 figure
An implementation of nDGP gravity in Pinocchio
In this paper we investigate dark matter structure formation in the normal
branch of the Dvali-Gabadadze-Porrati (nDGP) model using the PINOCCHIO
algorithm. We first present 2nd order Lagrangian perturbation theory for the
nDGP model, which shows that the 1st- and 2nd-order growth functions in nDGP
are larger than those in {\Lambda}CDM. We then examine the dynamics of
ellipsoidal collapse in nDGP, which is accelerated compared to {\Lambda}CDM due
to enhanced gravitational interactions. Running the nDGP-PINOCCHIO code with a
box size of 512 Mpc/h and 1024*1024*1024 particles, we analyze the statistical
properties of the output halo catalogs, including the halo power spectrum and
halo mass function. The calibrated PINOCCHIO halo power spectrum agrees with
N-body simulations within 5% in the comoving wavenumber range k < 0.3 (h/Mpc)
at redshift z = 0. The agreement is extended to smaller scales for higher
redshifts. For the cumulative halo mass function, the agreement between N-body
and PINOCCHIO is also within the simulation scatter.Comment: 18 pages, 3 figure
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