Paper-based spintronics: Magneto-resistivity of permalloy onto paper substrates

Abstract

Driven by low-cost, resource abundance and distinct material properties, the use of paper in electronics, optics and fluidics is under investigation. In order to realize a dense coverage of sensor networks as part of the roadmap of the internet-of-things, achieving lower manufacturing cost of the aforementioned sensors is required. Considering sensor systems based on magneto-resistance principles (anisotropic, giant, tunnel) that are conventionally manufactured onto inorganic semiconductor materials, we propose the use of paper substrates for cost reduction purposes primarily. In particular, we studied the magneto-resistance sensitivity of permalloy (Py:Ni 81 Fe 19 ) onto paper substrates. In this work, we report on our findings with clean room paper (80 g/m², R rms = 2.877 µm, 23% surface porosity, latex impregnation, no embossed macro-structure). Here, the Py:Ni 81 Fe 19 coating was manufactured by means of a dry process, sputter deposition, and spans an area of 10x10 mm² and a thickness of 70 nm. Employing a four-point-probe DC resistivity measurement setup, we investigated the change of electrical resistance of Py:Ni 81 Fe 19 under the presence of an oriented external magnetic field. In particular, we investigate the magneto-resistive change at two configurations: (1) the direction of the magnetic field is parallel to the nominal induced electric current and (2) the direction of the magnetic field is perpendicular to the electric current. Due to the stochastic orientation of the fibers interplaying with the Py:Ni 81 Fe 19 coating, the change in magneto-resistance of the overall system at both measurement configurations closely corresponds to the classical response of Py:Ni 81 Fe 19 at a ±45° angle between the direction of electrical current and magnetic field. Using the magneto-optic kerr effect, we observed the formation of domain walls at the fiber bending locations. Future work will focus on the impact of layer thickness, fiber dimensions and structure of magnetic coating on the performance of the paper-based Py:Ni 81 Fe 19 magnetoresistors.

Transparent Electrode and Magnetic Permalloy Made from Novel Nanopaper

“…In recent years, new organic platforms have been investigated for the implementation of magnetoelectronics in order to fulfill the requirements of the internet of things and people, such as low-cost and wearability. Previous research , has shown that the surface properties and the thermomechanical budget of commercially available paper constitute the bottleneck to the realization of high-performing thin film magnetics and magnetoelectronics. The surface roughness of a conventional paper platform induces pinning sites to the magnetic domains during magnetization of the thin film magnetic coating, reducing its sensitivity and delaying its response to an externally applied magnetic field .…”