Challenges of scanning hall microscopy using batch fabricated probes

Kodai Hatakeyama

Research output: ThesisPhD Thesis - Research UT, graduation UT

Abstract

Scanning Hall probe microscopy is a widely used technique for quantitative high resolution imaging of magnetic stray fields. Up to now probes with nanometer spatial resolution have only been realized by electron beam lithography, which is a slow and expensive fabrication technique. In this thesis, we employ corner lithography to enable batch fabrication of high resolution scanning Hall probes. The initial design consisted of a sub-&m Hall cross supported by four free standing wires in a pyramidal configuration, located at the end of an AFMtype cantilever. This implementation was mechanically and electrically too fragile to operate. Therefore the design was improved by supporting the wires with a robust silicon-nitride membrane. These robust probes allowed for scanning operation, but we discovered that the output signals suffered from large topographic crosstalk. We determined that this crosstalk was caused by the combination of cross asymmetry, resulting from fabrication imperfections, and topography induced probe-sample distance modulation, leading to temperature variation. To circumvent the crosstalk, we introduced an electronic compensation method to suppress the effect of temperature variation on the detected Hall signal. The method suppresses the temperature effect by at least a factor of ten, provided that the probe temperature varies uniformly over the entire structure. However, the method is not capable of compensating temperature changes within the probe structure itself, for instance caused by asymmetric probe cooling at step edges on the sample, or cantilever torsion. To increase the signal-to-noise ratio and improve the electrical robustness of the probes even more, we improved the probe design further by widening the leads to the Hall cross and increasing its dimensions. Using this final design, we successfully demonstrated imaging on a thermo-magnetically patterned magnetic sample with domains of 10 &m£10 &m, at a sensitivity of 4.12 V/T.
LanguageEnglish
Awarding Institution
  • University of Twente
Supervisors/Advisors
  • Abelmann, Leon , Supervisor
  • Krijnen, Gijsbertus J.M., Supervisor
Award date2 Sep 2016
Place of PublicationEnschede
Print ISBNs978-90-365-4163-3
DOIs
StatePublished - 2 Sep 2016

Fingerprint

microscopy
scanning
probes
crosstalk
fabrication
lithography
wire
temperature probes
theses
torsion
nitrides
temperature
temperature effects
topography
signal to noise ratios
spatial resolution
asymmetry
electron beams
membranes
modulation

Keywords

  • IR-101056
  • METIS-317603

Cite this

@phdthesis{7b4693a466614fee80c5879e10840af4,
title = "Challenges of scanning hall microscopy using batch fabricated probes",
abstract = "Scanning Hall probe microscopy is a widely used technique for quantitative high resolution imaging of magnetic stray fields. Up to now probes with nanometer spatial resolution have only been realized by electron beam lithography, which is a slow and expensive fabrication technique. In this thesis, we employ corner lithography to enable batch fabrication of high resolution scanning Hall probes. The initial design consisted of a sub-&m Hall cross supported by four free standing wires in a pyramidal configuration, located at the end of an AFMtype cantilever. This implementation was mechanically and electrically too fragile to operate. Therefore the design was improved by supporting the wires with a robust silicon-nitride membrane. These robust probes allowed for scanning operation, but we discovered that the output signals suffered from large topographic crosstalk. We determined that this crosstalk was caused by the combination of cross asymmetry, resulting from fabrication imperfections, and topography induced probe-sample distance modulation, leading to temperature variation. To circumvent the crosstalk, we introduced an electronic compensation method to suppress the effect of temperature variation on the detected Hall signal. The method suppresses the temperature effect by at least a factor of ten, provided that the probe temperature varies uniformly over the entire structure. However, the method is not capable of compensating temperature changes within the probe structure itself, for instance caused by asymmetric probe cooling at step edges on the sample, or cantilever torsion. To increase the signal-to-noise ratio and improve the electrical robustness of the probes even more, we improved the probe design further by widening the leads to the Hall cross and increasing its dimensions. Using this final design, we successfully demonstrated imaging on a thermo-magnetically patterned magnetic sample with domains of 10 &m£10 &m, at a sensitivity of 4.12 V/T.",
keywords = "IR-101056, METIS-317603",
author = "Kodai Hatakeyama",
year = "2016",
month = "9",
day = "2",
doi = "10.3990/1.9789036541633",
language = "English",
isbn = "978-90-365-4163-3",
school = "University of Twente",

}

Hatakeyama, K 2016, 'Challenges of scanning hall microscopy using batch fabricated probes', University of Twente, Enschede. DOI: 10.3990/1.9789036541633

Challenges of scanning hall microscopy using batch fabricated probes. / Hatakeyama, Kodai.

Enschede, 2016. 78 p.

Research output: ThesisPhD Thesis - Research UT, graduation UT

TY - THES

T1 - Challenges of scanning hall microscopy using batch fabricated probes

AU - Hatakeyama,Kodai

PY - 2016/9/2

Y1 - 2016/9/2

N2 - Scanning Hall probe microscopy is a widely used technique for quantitative high resolution imaging of magnetic stray fields. Up to now probes with nanometer spatial resolution have only been realized by electron beam lithography, which is a slow and expensive fabrication technique. In this thesis, we employ corner lithography to enable batch fabrication of high resolution scanning Hall probes. The initial design consisted of a sub-&m Hall cross supported by four free standing wires in a pyramidal configuration, located at the end of an AFMtype cantilever. This implementation was mechanically and electrically too fragile to operate. Therefore the design was improved by supporting the wires with a robust silicon-nitride membrane. These robust probes allowed for scanning operation, but we discovered that the output signals suffered from large topographic crosstalk. We determined that this crosstalk was caused by the combination of cross asymmetry, resulting from fabrication imperfections, and topography induced probe-sample distance modulation, leading to temperature variation. To circumvent the crosstalk, we introduced an electronic compensation method to suppress the effect of temperature variation on the detected Hall signal. The method suppresses the temperature effect by at least a factor of ten, provided that the probe temperature varies uniformly over the entire structure. However, the method is not capable of compensating temperature changes within the probe structure itself, for instance caused by asymmetric probe cooling at step edges on the sample, or cantilever torsion. To increase the signal-to-noise ratio and improve the electrical robustness of the probes even more, we improved the probe design further by widening the leads to the Hall cross and increasing its dimensions. Using this final design, we successfully demonstrated imaging on a thermo-magnetically patterned magnetic sample with domains of 10 &m£10 &m, at a sensitivity of 4.12 V/T.

AB - Scanning Hall probe microscopy is a widely used technique for quantitative high resolution imaging of magnetic stray fields. Up to now probes with nanometer spatial resolution have only been realized by electron beam lithography, which is a slow and expensive fabrication technique. In this thesis, we employ corner lithography to enable batch fabrication of high resolution scanning Hall probes. The initial design consisted of a sub-&m Hall cross supported by four free standing wires in a pyramidal configuration, located at the end of an AFMtype cantilever. This implementation was mechanically and electrically too fragile to operate. Therefore the design was improved by supporting the wires with a robust silicon-nitride membrane. These robust probes allowed for scanning operation, but we discovered that the output signals suffered from large topographic crosstalk. We determined that this crosstalk was caused by the combination of cross asymmetry, resulting from fabrication imperfections, and topography induced probe-sample distance modulation, leading to temperature variation. To circumvent the crosstalk, we introduced an electronic compensation method to suppress the effect of temperature variation on the detected Hall signal. The method suppresses the temperature effect by at least a factor of ten, provided that the probe temperature varies uniformly over the entire structure. However, the method is not capable of compensating temperature changes within the probe structure itself, for instance caused by asymmetric probe cooling at step edges on the sample, or cantilever torsion. To increase the signal-to-noise ratio and improve the electrical robustness of the probes even more, we improved the probe design further by widening the leads to the Hall cross and increasing its dimensions. Using this final design, we successfully demonstrated imaging on a thermo-magnetically patterned magnetic sample with domains of 10 &m£10 &m, at a sensitivity of 4.12 V/T.

KW - IR-101056

KW - METIS-317603

U2 - 10.3990/1.9789036541633

DO - 10.3990/1.9789036541633

M3 - PhD Thesis - Research UT, graduation UT

SN - 978-90-365-4163-3

CY - Enschede

ER -