# Publications

### Oriol T. Valls

**Emergence of Triplet Correlations in Superconductor/Half Metallic
Nanojunctions with Spin Active Interfaces**K. Halterman and O.T. Valls,

*Phys. Rev. B 80, 104502 (2009)*
Download from http://arxiv.org/abs/0907.2688

**Abstract**

We study triplet pairing correlations induced in an SFS trilayer (where F is a
ferromagnet and S an ordinary $s$-wave superconductor) by spin flip
scattering at the interfaces, via the derivation and self consistent solution of the
appropriate Bogoliubov-de Gennes equations in the clean limit. We find
that the spin flip scattering generates $m=\pm 1$ triplet correlations,
odd in time and study the general spatial behavior of these and of $m=0$ correlations
as a function of position and of spin-flip strength, $H_{spin}$, concentrating on the case
where the ferromagnet is half-metallic. For certain values of $H_{spin}$, the triplet correlations
pervade the magnetic layer and can penetrate deeply into the superconductor.
The behavior we find depends very strongly on whether the singlet order parameter is
in the 0 or $\pi$ state, which must in turn be determined self-consistently.
We also present results for the density of states (DOS)
and for the local magnetization, which, due to spin-flip processes, is not in general aligned
with the magnetization of the half metal, and near the interfaces, rotates as a function
of position and $H_{spin}$.
The average DOS in both F and S is shown to exhibit various subgap bound states positioned
at energies that
depend strongly on the particular junction state and the spin flip scattering strength.