Hall devices having an active area of about ͑500 nm͒ 2 are fabricated by focused electron-beam-induced deposition. The deposited material consists of cobalt nanoparticles in a carbonaceous matrix. The realized devices have, at room temperature, a current sensitivity of about 1 V / AT, a resistance of a few kilo-ohms, and can be biased with a maximum current of about 1 mA. The room-temperature magnetic field resolution is about 10 T/Hz 1/2 at frequencies above 1 kHz. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1856134͔Magnetic sensors having submicrometer spatial resolution are key elements in several fundamental studies as well as industrial applications.1-4 Hall effect devices are emerging as one of the most suitable solutions. [4][5][6][7][8][9] The ordinary Hall effect is due to the Lorentz force acting on charge carriers in metals, semi-metals, and semiconductors.5 Magnetic materials show additional "Hall phenomena" which are, generally speaking, generated by spin-orbit interactions: the so-called extraordinary [10][11][12][13][14][15][16] and planar Hall effects. 17-20The local deposition of materials using a focused electron beam in the presence of a volatile precursor is a wellestablished technique for the maskless fabrication of submicrometer structures such as functionalized tips for scanning probe microscopy, 21-26 electrodes for local conductivity measurements, 27 solder bonds for carbon nanotubes studies, 28 nanowires, 29-33 and nanodots. 34 In this letter we demonstrate the possibility to grow highly sensitive cobaltcarbon submicrometer Hall devices by means of a focused electron beam. This flexible "single-step" process represents an alternative to the conventional "multisteps" methods, which are usually based on a combination of optical ͑or electron beam͒ lithography and focused ion beam milling. The realized devices show a strong extraordinary Hall effect, whereas the ordinary and planar Hall effects ͑in most of the devices͒ are relatively small.

Images directly visualizing the spatial spin-diffusion process are reported. The measurements were performed using a magnetic resonance force microscope. The field gradient associated with the force-detection experiment is large enough to affect the spin dynamics and a modified kinetics of the spin-diffusion process is observed. The effects of the gradient were compensated for by a pulse scheme and a pure Zeeman diffusion rate constant of D=(6.2+/-0.7)x10{-12} cm{2}/s in CaF2 was observed.

We report on the measurement of element-specific magnetic resonance spectra at gigahertz frequencies using x-ray magnetic circular dichroism (XMCD). We investigate the ferrimagnetic precession of Gd and Fe ions in Gd-substituted Yttrium Iron Garnet, showing that the resonant field and linewidth of Gd precisely coincide with Fe up to the nonlinear regime of parametric excitations. The opposite sign of the Gd x-ray magnetic resonance signal with respect to Fe is consistent with dynamic antiferromagnetic alignment of the two ionic species. Further, we investigate a bilayer metal film, Ni 80 Fe 20 (5 nm)/Ni(50 nm), where the coupled resonance modes of Ni and Ni 80 Fe 20 are separately resolved, revealing shifts in the resonance fields of individual layers but no mutual driving effects. Energy-dependent dynamic XMCD measurements are introduced, combining x-ray absorption and magnetic resonance spectroscopies.

Abstract-An innovative release method of polymer cantilevers with embedded integrated metal electrodes is presented. The fabrication is based on the lithographic patterning of the electrode layout on a wafer surface, covered by two layers of SU-8 polymer: a 10-m-thick photo-structured layer for the cantilever, and a 200-m-thick layer for the chip body. The releasing method is based on dry etching of a 2-m-thick sacrificial polysilicon layer. Devices with complex electrode layout embedded in free-standing 500-m-long and 100-m-wide SU-8 cantilever were fabricated and tested. We have optimized major fabrication steps such as the optimization of the SU-8 chip geometry for reduced residual stress and for enhanced underetching, and by defining multiple metal layers [titanium (Ti), aluminum (Al), bismuth (Bi)] for improved adhesion between metallic electrodes and polymer. The process was validated for a miniature 2 2 m 2 Hall-sensor integrated at the apex of a polymer microcantilever for scanning magnetic field sensing. The cantilever has a spring constant of =1 N/m and a resonance frequency of =17 kHz. Galvanometric characterization of the Hall sensor showed an input/output resistance of 200 , a device sensitivity of 0.05 V/AT and a minimum detectable magnetic flux density of 9 T/Hz 1 2 at frequencies above 1 kHz at room temperature. Quantitative magnetic field measurements of a microcoil were performed. The generic method allows for a stable integration of electrodes into polymers MEMS and it can readily be used for other types of microsensors where conducting metal electrodes are integrated in cantilevers for advanced scanning probe sensing applications.[1573]Index Terms-Dry etch, Hall sensor, integrated electrodes, polysilicon sacrificial layer, stress-reducing geometries, SU-8 cantilever, thin film metal deposition and lift off.

A new technology based on a combination of Al-protection layers and HF-vapor etching to produce ultrathin single crystal silicon cantilevers is presented. 500 lm long, 10 lm wide and 0.5 lm thick cantilevers have been fabricated with a high yield. A resonance frequency of 2 kHz, Q factor >100,000 and a force sensitivity of 6.0 · 10 À17 N/Hz 1/2 have been obtained in vacuum at room temperature for cantilevers annealed at 800°C.