Reorientation Response of Magnetic Microspheres Attached to Gold Electrodes Under an Applied Magnetic Field

In this work, we report the mechanical reorientationof thiolated ferromagnetic microspheres bridging a pairof gold electrodes under an external magnetic field. Whenan external magnetic field (7 kG) is applied during themeasurement of the current–voltage characteristics of a carboxylferromagnetic microsphere (4 μm diameter) attachedto two gold electrodes by self-assembled monolayers(SAMs) of octane dithiol (C8H18S2), the current signal isdistorted. Rather than due to magnetoresistance, this effectis caused by a mechanical reorientation of the ferromagneticsphere, which alters the number of SAMs between thesphere and the electrodes and therefore affects conduction.To study the physical reorientation of the ferromagneticparticles, we measure their hysteresis loops while suspendedin a liquid solution.Keywords Magnetic microparticles