A novel approach to tune the ferromagnetic resonance frequency of a soft magnetic Ni 80 Fe 20 (Permalloy = Py) film with in-plane magnetic anisotropy (IMA) based on the controlled coupling to a hard magnetic NdCo x film with perpendicular magnetic anisotropy (PMA) through a non-magnetic Al spacer is studied. Using transverse magneto-optical Kerr effect (TMOKE), alternating gradient magnetometry (AGM) as well as vector network analyzer ferromagnetic resonance (VNA-FMR) spectroscopy, the influence of both Co concentration and Al spacer thickness on the static and dynamic magnetic properties of the coupled IMA/PMA system is investigated. Compared to a single Py film, two striking effects of the coupling between IMA and PMA layers can be observed in their FMR spectra. First, there is a significant increase in the zero-field resonance frequency from 1.3 GHz up to 6.6 GHz, and second, an additional frequency hysteresis occurs at low magnetic fields applied along the hard axis. The maximum frequency difference between the frequency branches for increasing and decreasing magnetic field is as high as 1 GHz, corresponding to a tunability of about 20% at external fields of typically less than ±70 mT. The origin of the observed features in the FMR spectra is discussed by means of magnetization reversal curves.The magnetic properties of thin films and multilayers exhibiting stripe domains have been investigated extensively in both experiment and theory since their discovery more than half a century ago 1 . In recent years, research results on stripe domains have triggered the prospect of employing their unique properties in future microwave, magnonic, and spintronic devices with novel functionalities. The formation of stripe domains is the result of energy minimization as well as the competition between PMA (K ⊥ ) and shape anisotropy ( 1 2 µ 0 M 2 S ), which favor out-of-plane and in-plane magnetization, respectively. The ratio Q = 2K ⊥ /µ 0 M 2 S , known as reduced anisotropy or quality factor 2 , is commonly used to describe the extent of stripe domains. For moderate (Q < 1) to weak (Q 1) PMA, the magnetization tends to lie in the plane, but above a critical film thickness d cr , a ground state with stripe domains emerges. The latter is characterized by a perpendicular magnetization component alternating between up and down within a period λ . The critical thickness d cr is typically in the range of 20 -40 nm for moderate Q value materials such as amorphous NdCo alloys 3,4 , whereas for materials like Py with small values of Q, generally larger values of d cr = 170 -300 nm are found 5-8 . Intimately linked to the presence of stripe domains is the occurrence of a pseudo-uniaxial or rotatable anisotropy 9,10 , which is the result of the in-plane magnetization being aligned along the stripe direction. The latter, however, is not fixed as it can be reoriented by applya) Electronic

We have designed, fabricated and tested a robust superconducting ratchet device based on topologically frustrated spin-ice nanomagnets. The device is made of a magnetic Co honeycomb array embedded in a superconducting Nb film. This device is based on three simple mechanisms: i) the topology of the Co honeycomb array frustrates in-plane magnetic configurations in the array yielding a distribution of magnetic charges which can be ordered or disordered with in-plane magnetic fields, following spin-ice rules; ii) the local vertex magnetization, which consists of a magnetic half vortex with two charged magnetic Néel walls; iii) the interaction between superconducting vortices and the asymmetric potentials provided by the Néel walls. The combination of these elements leads to a superconducting ratchet effect. Thus, superconducting vortices driven by alternating forces and moving on magnetic half vortices generate a unidirectional net vortex flow. This ratchet effect is independent of the distribution of magnetic charges in the array.

Perpendicular magnetic anisotropy ferromagnetic/superconducting (FM/SC) bilayers with a labyrinth domain structure are used to study nucleation of superconductivity on a fractal network, tunable through magnetic history. As clusters of reversed domains appear in the FM layer, the SC film shows a percolative behavior that depends on two independent processes: the arrangement of initial reversed domains and the fractal geometry of expanding clusters. For a full labyrinth structure, the behavior of the upper critical field is typical of confined superconductivity on a fractal network.

Films of four different nanostructures, namely micelles, filled cylinders, ring-shaped porous nanostructures and hollow cylinders, can be prepared easily in a straightforward and simple way by spin coating onto a silicon plate toluene solutions of poly(styrene-block-4-vinylpyridine) copolymer containing formic acid of increasing concentration. Despite the enormous progress in preparation of porous polymers, most of them require multiple steps. In this sense, this method represents an effort to obtain not only porous thin films but also other bidimensional nanostructures in a very simple way.

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