Combination with transport measurements

Our wide-field Kerr microscopes are predestined for combination with electrical transport measurements. The sample space in our microscopes is sufficiently large so that any type of electrical contacting can easily be realized. The only requirement is that the sample site to be imaged is freely accessible for the microscope objective (long distance objectives can be advantageous here). Our Kerr microscopes can also be combined with commercial probe stations of the customer’s choice.

Self-assembly of Co/Pt stripes with current-induced domain wall motion towards 3D racetrack devices

P. Fedorov, I. Soldatov, V. Neu, R. Schäfer, O. G Schmidt, D. Karnaushenko

Nature Communications, 15, 2048 (2024)

Modification of the magnetic properties under the induced strain and curvature is a promising avenue to build three-dimensional magnetic devices, based on the domain wall motion. So far, most of the studies with 3D magnetic structures were performed in the helixes and nanowires, mainly with stationary domain walls. In this study, we demonstrate the impact of 3D geometry, strain and curvature on the current-induced domain wall motion and spin-orbital torque efficiency in the heterostructure, realized via a self-assembly rolling technique on a polymeric platform. We introduce a complete 3D memory unit with write, read and store functionality, all based on the field-free domain wall motion. Additionally, we conducted a comparative analysis between 2D and 3D structures, particularly addressing the influence of heat during the electric current pulse sequences. Finally, we demonstrated a remarkable increase of 30% in spin-torque efficiency in 3D configuration.

Antiskyrmions and their electrical footprint in crystalline mesoscale structures of Mn_1.4PtSn

M. Winter, F. J. T. Goncalves, I. Soldatov, Y. He, B. E. Z. Céspedes, P. Milde, K. Lenz, S. Hamann, M. Uhlarz, P. Vir, M. König, P. J. W. Moll, R. Schlitz, S. T. B. Goennenwein, L. M. Eng, R. Schäfer, J. Wosnitza, C. Felser, J. Gayles & Toni Helm

Communications materials, 3, 102 (2022)

Skyrmionic materials hold the potential for future information technologies, such as racetrack memories. Key to that advancement are systems that exhibit high tunability and scalability, with stored information being easy to read and write by means of all-electrical techniques. Topological magnetic excitations such as skyrmions and antiskyrmions, give rise to a characteristic topological Hall effect. However, the electrical detection of antiskyrmions, in both thin films and bulk samples has been challenging to date. Here, we apply magneto-optical microscopy combined with electrical transport to explore the antiskyrmion phase as it emerges in crystalline mesoscale structures of the Heusler magnet Mn_1.4PtSn. We reveal the Hall signature of antiskyrmions in line with our theoretical model, comprising anomalous and topological components. We examine its dependence on the vertical device thickness, field orientation, and temperature. Our atomistic simulations and experimental anisotropy studies demonstrate the link between antiskyrmions and a complex magnetism that consists of competing ferromagnetic, antiferromagnetic, and chiral exchange interactions, not captured by micromagnetic simulations.

Self-assembly as a tool to study microscale curvature and strain-dependent magnetic properties

B. Singh, J. A. Otálora, T. H. Kang, I. Soldatov, D. D. Karnaushenko, C. Becker, R. Schäfer, D. Karnaushenko, V. Neu, O. G. Schmidt

Flexible Electronics, 6, 76 (2022)

The extension of 2D ferromagnetic structures into 3D curved geometry enables to tune its magnetic properties such as uniaxial magnetic anisotropy. Tuning the anisotropy with strain and curvature has become a promising ingredient in modern electronics, such as flexible and stretchable magnetoelectronic devices, impedance-based field sensors, and strain gauges, however, has been limited to extended thin films and to only moderate bending. By applying a self-assembly rolling technique using a polymeric platform, we provide a template that allows homogeneous and controlled bending of a functional layer adhered to it, irrespective of its shape and size. This is an intriguing possibility to tailor the sign and magnitude of the surface strain of integrated, micron-sized devices. In this article, the impact of strain and curvature on the magnetic ground state and anisotropy is quantified for thin-film Permalloy micro-scale structures, fabricated on the surface of the tubular architectures, using solely electrical measurements.