We report on first-principles calculations of spin-dependent properties in graphene induced by its interaction with a nearby magnetic insulator (europium oxide, EuO). The magnetic proximity effect results in spin polarization of graphene π orbitals by up to 24%, together with a large exchange-splitting band gap of about 36 meV. The position of the Dirac cone is further shown to depend strongly on the graphene-EuO interlayer. These findings point toward the possible engineering of spin gating by the proximity effect at a relatively high temperature, which stands as a hallmark for future all-spin information processing technologies.

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We study the physical properties of a ballistic heterostructure made of a ferromagnet (FM) and a spin-triplet superconductor (TSC) with a layered structure stacking along the direction perpendicular to the planes where a chiral px+ipy pairing occurs and assuming spin dependent processes at the interface. We use a self-consistent Bogoliubov-de Gennes approach on a three-dimensional lattice to obtain the spatial profiles of the pairing amplitude and the magnetization. We find that, depending on the strength of the ferromagnetic exchange field, the ground state of the system can have two distinct configurations with a parallel or anti-parallel collinearity between the magnetic moments in the bulk and at the interface. We demonstrate that a magnetic state having non coplanar interface, bulk and Cooper pairs spins may be stabilized if the bulk magnetization is assumed to be fixed along a given direction. The study of the density of states reveals that the modification of the electronic spectrum in the FM plays an important role in the setting of the optimal magnetic configuration. Finally, we find the existence of induced spin-polarized pair correlations in the FM-TSC system.

We study the spin and charge currents flowing at the interface of an itinerant ferromagnet with a topological spin-triplet superconductor having different number of time-reversal-invariant Majorana helical modes. Depending on the number of helical modes, the capacity of carrying spin and charge currents is shown to be directly related to the amplitude and orientation of the ferromagnetic magnetization with respect to the superconducting d-vector. Differently from the one-helical mode spin-triplet superconductor, we find that the presence of a finite amount of electronic hybridization with the two pairs of Majorana helical modes leads to nonvanishing charge current independently of the ferromagnetic exchange. The competition between the two pairs of Majorana helical modes remarkably yields a spin-current response that is almost constant in the range of weak to intermediate ferromagnetism. The behavior of the spin current is tightly linked to the direction of the spinpolarization in the ferromagnet and tends to be flatten for a magnetization that is coplanar to the spin-triplet d-vector independently of the number of helical modes.

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