Batch fabricated sensors for magnetic force microscopy

Abstract

Electron beam patterned permalloy circular dots of 700 nm diameter with small separations were studied by magnetic force microscopy (MFM) in the presence of an in situ magnetic field. Images in the demagnetized state show that the dot is in a vortex state with a vortex core (singularity) in the center. Local hysteresis loops, measured by cantilever frequency shift in an external field, indicate that the magnetization reversal of individual disks is a vortex nucleation and annihilation process. By carefully doing MFM, nucleation and annihilation fields without MFM tip stray field distortions are obtained. Configurational anisotropy originated from magnetostatic coupling is found through hysteresis loops. © 2002 American Institute of Physics

Applications of Magnetic Force Microscopy

“…This was demonstrated directly by imaging magnetically soft samples, corroborated by simulations and confirmed by Lorentz microscopy of tip stray fields [17,18]. This allows the imaging of NiFe (Permalloy) with no noticeable tip-induced domain motion [14,17]. Furthermore, the magnetic properties of thin-film tips can be tailored.…”

“…Their stray field is much smaller due to the volume reduction of magnetic tip material without a corresponding loss of sensitivity [17]. This was demonstrated directly by imaging magnetically soft samples, corroborated by simulations and confirmed by Lorentz microscopy of tip stray fields [17,18]. This allows the imaging of NiFe (Permalloy) with no noticeable tip-induced domain motion [14,17].…”

“…Thin-film tips have several advantages over bulk ferromagnetic tips. Their stray field is much smaller due to the volume reduction of magnetic tip material without a corresponding loss of sensitivity [17]. This was demonstrated directly by imaging magnetically soft samples, corroborated by simulations and confirmed by Lorentz microscopy of tip stray fields [17,18].…”

“…Etched Ni wires or Co galvanically deposited on etched W tips have been used with success (see [2] for a list of references with detailed procedures). More recently, micromachined cantilevers with bulk ferromagnetic NiFe tips ( [16]) or thin-film coated Si tips have been developed [17]. Besides the possibility of batch fabrication, micromachined cantilevers have superior mechanical properties compared to etched wires, thus increasing the sensitivity for the detection of small interactions.…”

Magnetic Force Microscopy — Towards Higher Resolution

“…We can however indicate different categories. The most common magnetic coating is an alloy based on Co with additions such as Cr and Pt, based on the pioneering work of Grütter et al [9,10]. These alloys are often derived from hard disk recording layer materials and have a high coercivity.…”