Artificial magnetoception is a new and yet to be explored path for humans to interact with the surroundings. This technology is enabled by thin film magnetic field sensors embedded in a soft and flexible format to constitute magnetosensitive electronic skins (e-skins). Being limited by the sensitivity to in-plane magnetic fields, magnetosensitive e-skins are restricted to basic proximity and angle sensing and are not used as switches or logic elements of interactive wearable electronics. Here, a novel magnetoreceptive platform for on-skin touchless interactive electronics based on flexible spin valve switches with sensitivity to out-of-plane magnetic fields is demonstrated. The technology relies on all-metal Co/Pd-based spin valves with a synthetic antiferromagnet possessing perpendicular magnetic anisotropy. The flexible magnetoreceptors act as logic elements, namely momentary and permanent (latching) switches. The switches maintain their performance even upon bending to a radius of less than 3.5 mm and withstand repetitive bending for hundreds of cycles. Here, flexible switches are integrated in on-skin interactive electronics and their performance as touchless human-machine interfaces is demonstrated, which are intuitive to use, energy efficient, and insensitive to external magnetic disturbances. This technology offers qualitatively new functionalities for electronic skins and paves the way towards full-fledged on-skin touchless interactive electronics.

The interaction between surface acoustic waves (SAWs) and spin waves (SWs) in a piezoelectric/magnetic thin film heterostructure yields potential for the realization of novel microwave devices and applications in magnonics. In the present work, we investigate the SAW-SW interaction in a Pt/Co(2 nm)/Ru(0.85 nm)/Co(4 nm)/Pt synthetic antiferromagnet (SAF) composed of two ferromagnetic layers with different thicknesses separated by a thin nonmagnetic Ru spacer layer. Because of the combined presence of interfacial Dzyaloshinskii-Moriya interaction (iDMI) and interlayer dipolar coupling fields, the optical SW mode shows a large nondegenerate dispersion relation for oppositely propagating SWs. Due to SAW-SW interaction, we observe nonreciprocal SAW transmission in the piezoelectric/SAF hybrid device. The equilibrium magnetization directions of both Co layers are manipulated by an external magnetic field to set a ferromagnetic, canted, or antiferromagnetic configuration. This has a strong impact on the SW dispersion, its nonreciprocity, and SAW-SW interaction. The experimental results are in agreement with a phenomenological SAW-SW interaction model, which considers the interlayer exchange coupling, iDMI, and interlayer dipolar coupling fields of the SWs.

Flexible magneto-resistive heterostructures have received a great deal of attention over the past few years as they allow for new product paradigms that are not possible with conventional rigid substrates....

Thin film stacks made of multiple repeats of Co/Pd-based SAF units with perpendicular magnetic anisotropy and tunable magnetic moment were explored as starting material to fabricate free-standing micro/nanodisks for theranostic applications.

No abstract

Nanostructured α-Mn3O4 (haussmannite) thin films consisting of evenly interconnected nanoaggregates were prepared on Si(100) substrates by chemical vapor deposition from a Mn­(II) diketonate-diamine precursor under different reaction atmospheres (dry vs wet O2) and total operating pressures. The combination of chemico-physical results obtained by the joint use of complementary techniques enabled us to demonstrate the obtainment of high-purity Mn3O4 materials free from other manganese oxide phases, characterized by controllable structural and morphological characteristics as a function of the adopted processing conditions. Magnetic properties were investigated by analyzing temperature dependence (i.e., field-cooled and zero-field-cooled measurements) and field-dependence of the magnetization behavior. The obtained films show bulk-like magnetic properties, together with extraordinarily high low-temperature in-plane coercivities (up to ∼1 T). The possibility to tailor these values by varying the content of microstructural defects may foster the implementation of the obtained films in eventual technological applications.

No abstract

Synthetic antiferromagnets with perpendicular magnetic anisotropy (PMA-SAFs) have gained growing attention for both conventional and nextgeneration spin-based technologies. While the progress of PMA-SAF spintronic devices on rigid substrates has been remarkable, only few examples of flexible thin-film heterostructures are reported in the literature, all containing platinum group metals (PGMs). Systems based on Co/Ni may offer additional advantages with respect to devices containing PGMs, i.e., low damping and high spin polarization. Moreover, limiting the use of PGMs may relieve the demand for critical raw materials and reduce the environmental impact of related technologies, thus contributing to the transition toward a more sustainable future. Here, we discuss for the first time the realization of Co/Ni-based PMA-SAFs on polymer tapes and exploit it to obtain flexible giant magneto-resistive spin valves (GMR-SVs) with perpendicular magnetic anisotropy. Several combinations of buffer and capping layers (i.e., Pt, Pd, and Cu/Ta) are also investigated. High-quality flexible SAFs with a fully compensated antiferromagnetic region and SVs with a sizable GMR ratio (up to 4.4%), in line with the values reported in the literature for similar systems on rigid substrates, were obtained in all cases. However, we demonstrate that PGMs allows achieving the best results when used as a buffer layer, while Cu is the best choice as a capping layer to optimize the properties of the stacks. We justify the role of buffer and capping layers in terms of different interdiffusion mechanisms occurring at the interface between the metallic layers. These results, along with the high robustness of the samples' properties against bending (up to 180°), indicate that complex and bendable Co/Ni-based heterostructures with reduced content of PGMs can be obtained on flexible tapes, allowing for the development of novel flexible and sustainable spintronic devices for applications in many fields including wearable electronics, soft robotics, and biomedicine.