Direct and real-time observation of sub-micron domain dynamics in magnetically biased strontium ferrite permanent magnets by room temperature scanning micro-Hall probe microscopy

Date

2001-01-01

Author

Sandhu, Adarsh
Iida, Naoji
Masuda, Hiroshi
Oral, Ahmet
Bending, Simon J.

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A room temperature scanning micro-Hall probe microscope (RT-SHPM) was used for imaging stray magnetic field fluctuations at the surfaces of strontium ferrite permanent magnets (SFM) in the presence of external bias fields. The RT-SHPM enables the extremely fast, non-invasive, and quantitative measurement of localized surface magnetic fields on the sub-micron-scale. A 0.8 × 0.8 μm2 GaAs/AlGaAs micro-Hall probe (300K Hall coefficient = 0.3Ω/G; field sensitivity = 0.04 G/√Hz) with an integrated STM tip for precise vertical positioning was used as a magnetic field sensor. External bias fields (Hex) of up to 2700 Oe were applied parallel to the easy and hard axes of thermally demagnetized SFMs. Sample areas of up to 50×50 μm were imaged at a height of 0.3 μm above the SFM surface for each Hex, with scan speeds of approximately one frame/second (128×128 pixels) enabling quasi-real time imaging in synchronization with bias field changes. RT-SHPM images of surfaces normal to the easy axis of demagnetized samples at Hex = 0, clearly showed the presence of 8-15 μm sized domains and stray magnetic field fluctuations of ±200G; images of surfaces normal to the hard axis showed 20 μ sized domains with magnetic field fluctuations of ±100G. Pronounced domain movement and rotation was observed for surfaces normal to the easy axis at bias fields above 700 Oe applied along the easy axis. A good correlation was found between domain movement and vibrating sample magnetometer hysteresis measurements. The RT-SHPM system was demonstrated to be a valuable tool for the direct and non-invasive study of micro-magnetic phenomena in ferromagnetic materials.

URI

https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0035557828&origin=inward
https://hdl.handle.net/11511/94546

DOI

https://doi.org/10.1557/proc-674-u3.2

Conference Name

Applications of Ferromagnetic and Optical Materials, Storage and Magnotoelectronics

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Department of Physics, Conference / Seminar

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Direct and real-time observation of sub-micron domain dynamics in magnetically biased strontium ferrite permanent magnets by room temperature scanning micro-Hall probe microscopy Sandhu, Adarsh; Iida, Naoji; Masuda, Hiroshi; Oral, Ahmet; Bending, Simon J. (2001-01-01) A room temperature scanning micro-Hall probe microscope (RT-SHPM) was used for imaging stray magnetic field fluctuations at the surfaces of strontium ferrite permanent magnets (SFM) in the presence of external bias fields. The RT-SHPM enables the extremely fast, non-invasive, and quantitative measurement of localized surface magnetic fields on the sub-micron-scale. A 0.8 × 0.8 μm2 GaAs/AlGaAs micro-Hall probe (300K Hall coefficient = 0.3Ω/G; field sensitivity = 0.04 G/√Hz) with an integrated STM tip for pre...
Direct magnetic imaging of ferromagnetic domain structures by room temperature scanning hall probe microscopy using a bismuth micro-hall probe SANDHU, ADARSH; MASUDA, HİROSHİ; Oral, Ahmet; BENDİNG, SİMON J (IOP Publishing, 2001-05-15) A bismuth micro-Hall probe sensor with an integrated scanning tunnelling microscope tip was incorporated into a room temperature scanning Hall probe microscope system and successfully used for the direct magnetic imaging of microscopic domains of low coercivity perpendicular garnet thin films and demagnetized strontium ferrite permanent magnets. At a driving current of 800 muA, the Hall coefficient, magnetic field sensitivity and spatial resolution of the Bi probe were 3.3 x 10(-4) Omega /G, 0.38 G/root Hz ...
Magnetic imaging of ferromagnetic domains by room temperature scanning hall probe microscopy using GaAs/AlGaAs and bismuth micro-hall probes Sandhu, A.; Masuda, H.; Oral, Ahmet; Bending, S.J.; Inushima, T. (2002-01-01) Heterostructure GaAs/AlGaAs and bismuth (Bi) micro-Hall probes were integrated into a room temperature scanning Hall probe microscope system (RT-SHPM) for imaging localized magnetic fluctuations at the surfaces of floppy disks, crystalline garnet thin films, and strontium ferrite permanent magnets. At a drive current of 800 μA the sensitivity of the Bi micro-probes was 0.38 G/√ Hz and comparable with the GaAs/AlGaAs probes. Bi nano-Hall probes with an active region of 200 nm × 200 nm were fabricated by focu...
Analysis of reconstruction performance of magnetic resonance conductivity tensor imaging (MRCTI) using simulated measurements DEĞİRMENCİ, EVREN; Eyüboğlu, Behçet Murat (2017-01-01) Magnetic resonance conductivity tensor imaging (MRCTI) was proposed recently to produce electrical conductivity images of anisotropic tissues. Similar to magnetic resonance electrical impedance tomography (MREIT), MRCTI uses magnetic field and boundary potential measurements obtained utilizing magnetic resonance imaging techniques. MRCTI reconstructs tensor images of anisotropic conductivity whereas MREIT reconstructs isotropic conductivity images. In this study, spatial resolution and linearity of five rec...
Room temperature sub-micron magnetic imaging by scanning Hall probe microscopy SANDHU, ADARSH; MASUDA, HİROSHİ; Oral, Ahmet; BENDİNG, SİMON J (IOP Publishing, 2001-06-01) An ultra-high sensitive room temperature scanning Hall probe microscope (RT-SHPM) system incorporating a GaAs/AlGaAs micro-Hall probe was used for the direct magnetic imaging of localized magnetic field fluctuations in very close proximity to the surface of ferromagnetic materials. The active area, Hall coefficient and field sensitivity of the Hall probe were 0.8 mum x 0.8 mum, 0.3 Omega /G and 0.04G/root Hz, respectively. The use of a semiconducting Hall probe sensor enabled measurements in the presence of...

Citation Formats

A. Sandhu, N. Iida, H. Masuda, A. Oral, and S. J. Bending, “Direct and real-time observation of sub-micron domain dynamics in magnetically biased strontium ferrite permanent magnets by room temperature scanning micro-Hall probe microscopy,” San Francisco, CA, Amerika Birleşik Devletleri, 2001, vol. 674, Accessed: 00, 2021. [Online]. Available: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0035557828&origin=inward.