Within the talk I will review our activity on spintronic applications which is done in close cooperation with the industrial partner Infineon AG. The advantage of topological charged vortex structure for sensor application for low noise speed sensors will be reported that will be commercialized by Infineon for ABS systems in cars in 2018.
As a second example, we will review the potential of...
Perpendicularly magnetized nanowires exhibit distinct domain wall types depending on the geometry. Wide wires contain Bloch walls, narrow wires Néel walls. Here, the transition region is investigated by direct imaging of the wall structure using high-resolution spin-polarized scanning electron microscopy. An achiral wall type is discovered whose in-plane magnetic moment angle is intermediate...
We study theoretically the triangular-lattice, Ising antiferromagnet with long-range dipolar interactions, inspired by its realisation in nano-magnet arrays. We show that a classical spin-liquid regime exists above a low-temperature ordered phase, and explore how the nature of the spin liquid can be altered by a small lattice deformation. Deforming the lattice also tunes the nature of the...
Quasistatic studies on artificial quasicrystals reported exotic properties such as knee anomalies in the magnetic hysteresis. Spin wave resonances may help to further understand their exotic properties.
We fabricated interconnected networks of nanobars (810 nm long, 130 nm wide) from 25 nm thick Permalloy and arranged them on Penrose P2, P3, and Ammann quasicrystal lattices. Performing...
Enhanced magnetism in 3d transition metal nanoparticles is of great interest for applications and for our fundamental understanding of nanomagnetism. However, despite considerable research efforts, the origin of anomalous magnetic properties in nanoparticles, such as enhanced magnetic anisotropy, are still poorly understood. Here, we combine X-ray photo-emission electron microscopy (X-PEEM)...
Antiferromagnetic materials play an important role in modern spintronics devices. While the properties of antiferromagnetic bulk materials are often well investigated, much less is known about their properties at the nanoscale. Here, we use X-ray photo-emission electron microscopy (X-PEEM) together with X-ray magnetic linear dichroism to study the magnetism of individual goethite...
Current-induced spin-orbit torques (SOTs) represent one of the most effective ways to manipulate the magnetization in spintronic devices. The orthogonal torque-magnetization geometry and the large domain wall velocities inherent to materials with strong spin-orbit coupling make SOTs appealing for fast switching applications in nonvolatile memory and logic units. Here, we report the first...
Magnetic Force Microscopy (MFM) is a versatile tool to map the stray field emanating from a sample surface with high spatial resolution and sensitivity, and in applied magnetic fields up to several Teslas.
The technical aspects of MFM will be reviewed and examples of high current interest such systems exhibiting interfacial Dzyaloshinskii-Moriya interaction (DMI) will be discussed. The average...
Skyrmions are topologically protected spin whirls envisaged as promising information carriers. In this talk, we report both writing and erasing skyrmions with moderate electric fields in Cu2OSeO3. Using neutron scattering, we demonstrate that the skyrmion pocket either expands or shrinks significantly depending on the direction of electric fields, allowing us to write or erase the skyrmion...
Magnetic skyrmions are topologically non-trivial nano-scale spin textures having raised great interest not only for their unique physical behaviors, but also for the potential applications in spintronics. In thin crystals of helical magnets, the skyrmion phase coexists with the topologically trivial helical and field-polarized phases over large portions of the phase diagram.
Here we use an...
Controlling magnetization using piezoelectric strain offers unprecedented power efficiency for next-generation spintronic devices. However, strain is a uniaxial effect and, unlike directional magnetic field or spin-polarized current, cannot induce a full 180° reorientation of the magnetization vector when acting alone. We have engineered novel “peanut” and “cat-eye” shaped nanomagnets on...
We study ultra-thin films of Fe magneto-electrically coupled with a ferroelectric substrate PMN-PT (001) .We have grown ultra-thin wedge of Fe with thickness varying from 1 ML to 5 ML on PMN-PT (001) under ultra-high vacuum conditions. We employed x-ray magnetic circular di-chroism (XMCD) technique at, the Fe L3, 2-edges. The results for the Fe wedge (1-5 ML) shows that the thinner part (1 ML)...
Charge-mediated control of magnetism has been found in many systems. Here we present an approach to controlling magnetism through field effects using a silicon nitride membrane as gate dielectric. A Pt/Co/Pt tri-layer structure is grown on a high resistance silicon nitride membrane and an electric field is applied out-of-plane. Magnetic characterization is performed with Magneto-optic Kerr...
Most of the digital information today is encoded in the magnetization of ferromagnetic domains. Writing a bit is usually achieved by rotating domains, which relies on magnetic fields. An alternative approach is to change the magnetic state directly by changing the interaction between spins. Correlated oxides are ideal materials for this because the effect of small external control parameter is...
The spin Hall effect in a current-carrying wire leads to the accumulation of spins at the outer edges of the wire. We detect this spin imbalance by magneto-optical Kerr microscopy and find that the Kerr rotation for Pt and W has opposite sign, as expected from the respective spin Hall angles. The measured spin accumulation scales linearly with the applied current density. In...
Recently we have combined a scanning transmission x-ray microscopy (STXM) setup with a novel microwave synchronization scheme for studying high frequency magnetization dynamics in the GHz regime [1] enabeling spatially resolved ferromagnetic resonance (FMR) studies on magnetic micro- and nanostructures. Compared to other spatially resolved FMR detection schemes [2] the STXM-FMR setup features...
