Superparamagnetic magnetic force microscopy tips

Hopkins, P. F.; Moreland, John; Malhotra, S.S.; Liou, Sy‐Hwang

doi:10.1063/1.361969

Cited by 44 publications

(16 citation statements)

References 9 publications

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“…When the scan height increases, the double-peak feature smears out. It is also consistent to our earlier results, 13 where we observed only a single peak, and the estimated gap width was about 2-3 times higher than the actual gap width. This was due to the large tip-sample distance ͑ϳ100 nm͒ used in the previous experiments.…”

Section: ͓S0003-6951͑97͒01701-4͔supporting

confidence: 82%

“…23 In this report, we show only the results obtained using a 80 nm Fe 70 ͑SiO 2 ) 30 tip coating which is twice the thickness used in the previous work. 13 The results obtained from using the Fe 70 ͑SiO 2 ) 30 tips with 40-nm-thick coatings are similar and have about half the frequency shift of the 80 nm tips. Figure 1 shows 10 m ϫ10 m images of a thin-film recording head using a Fe 70 ͑SiO 2 ) 30 superparamagnetic MFM tip with a coating thickness of 80 nm.…”

Section: ͓S0003-6951͑97͒01701-4͔supporting

confidence: 58%

“…13 In comparison to the MFM images taken using Co 85 Cr 15 coated tips, the MFM images using superparamagnetic tips shows reduced tip hysteresis effects and clearly delineate the gapfield profiles from the pole pieces.…”

Section: ͓S0003-6951͑97͒01701-4͔mentioning

confidence: 99%

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High resolution imaging of thin-film recording heads by superparamagnetic magnetic force microscopy tips

Liou

Malhotra

Moreland

et al. 1997

Applied Physics Letters

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Section: ͓S0003-6951͑97͒01701-4͔supporting

confidence: 82%

Section: ͓S0003-6951͑97͒01701-4͔supporting

confidence: 58%

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High resolution imaging of thin-film recording heads by superparamagnetic magnetic force microscopy tips

Liou

Malhotra

Moreland

et al. 1997

Applied Physics Letters

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“…We have identified the recording head of a computer hard disk drive as a convenient sample producing a well-defined magnetic force gradient [6]. In Fig.…”

Section: Introductionmentioning

confidence: 99%

Low temperature force microscopy based on piezoresistive cantilevers operating at a higher flexural mode

Volodin

Haesendonck

1998

Applied Physics A: Materials Science & Processing

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We present a method to considerably enhance the sensitivity of low-temperature force microscopy based on commercially available piezoresistive cantilevers. The sensitivity has been increased by using a higher flexural mode of the cantilever in the non-contact frequency modulation detection technique. The operation at higher (2 nd or 3 rd ) mechanical resonances (> 0.4 MHz) allows to improve the signalto-noise ratio by a factor of 3. This offers the possibility to considerably reduce the heat dissipation during the measurements. Our detection method is particularly advantageous for studying superconductor surfaces. Measurements illustrating the sensitivity and imaging capability of our new detection method are presented.The fabrication of cantilevers integrated with piezoresistive displacement detection sensors has resulted in a remarkable improvement of scanning force microscopies (SFM) in terms of applicability and ease of implementation [1,2]. The sensing element is a piezoresistor embedded in the arms of the cantilever. The resistance change of this piezoresistor caused by stresses due to cantilever deflection can easily be measured. These cantilevers are ideally suited for operation at low temperatures because they do not require optical detection of the cantilever deflection with the necessary in situ adjustments of the optical beam. On the other hand, an important problem for low-temperature applications of piezoresistive cantilevers is the heat dissipation when measuring variations of the piezoresistance. The output signal increases with the measuring current flowing through the piezoresistor. To achieve a performance comparable to the optical detection schemes, a current of about 2 mA is needed. The heat dissipation (several mW) caused by this current raises the cantilever temperature. According to the measurements of the shift of the cantilever eigenfrequency presented in [1], the temperature increase is about 31 K in vacuum and at room temperature. While such a temperature rise can be neglected at room temperature, a comparable rise at liquid helium temperatures (< 4.2 K) may strongly affect the SFM results. The heat dissipation also makes it necessary to use thermal exchange gas with relatively high densities, excluding the advantages of a high mechanical quality factor of the cantilever for an effective and sensitive frequency modulation detection. Hence, a decrease of the heat dissipation of piezoresistive cantilevers without lowering their performance is highly desirable for low-temperature applications.In this paper we present a method to considerably enhance the sensitivity of piezoresistive detection schemes, allowing to reduce the heat dissipation. Our method is based on the use of a higher flexural mode of the cantilever in the non-contact frequency modulation detection technique. Higher vibration modes of AFM cantilevers have already been used in the past for imaging purposes [3,4]. The flexural vibrations of AFM cantilevers have been investigated in detail [5]. It turned out that the higher m...

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“…As a result however, the tip is always attracted and one looses information on the polarity of the field. Materials used are for instance Co [10], NiFe [10], Fe [31] and granular Fe(SiO 2 ) films [11].…”

Section: Coating Of Afm Tipsmentioning

confidence: 99%

Magnetic Force Microscopy — Towards Higher Resolution

Abelmann¹,

Bos²,

Lodder³

2005

Magnetic Microscopy of Nanostructures

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Abstract. In this chapter Magnetic Force Microscopy is treated in detail. The emphasis is on high resolution and the design and realisation of MFM tips. Principle of MFMThe technique of Magnetic Force Microscopy has been discussed extensively in literature [8,20,12], so we will restrict ourselves to a short description. The principle of Magnetic Force Microscopy is very much alike that of Atomic Force Microscopy -some even dare to mention that MFM is just an AFM with a magnetic tip, much to the dislike of MFM developers because in an MFM much smaller forces are measured. In essence it is true however, and every MFM is capable of AFM as well (the other way round is not true in general).In an MFM the magnetic stray field above a very flat specimen, or sample, is detected by placing a small magnetic element, the tip, mounted on cantilever spring very close to the surface of the sample (figure 1). Typical dimensions are a cantilever length of 200 µm , tip length of 4 µm and diameter of 50 nm and a distance from the surface of 30 nm. The force on the magnetic tip is detected by measuring the displacement of the end of the cantilever, usually by optical means. The forces measured in typical MFM applications are in the order of 30 pN, with typical cantilever deflections in the order of nanometers.An image of the magnetic stray field is obtained by slowly scanning the cantilever over the sample surface, in a raster-like fashion. Typical scan area's are from 1 up to 200 µm with imaging times in the order of 5-30 minutes.

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Superparamagnetic magnetic force microscopy tips

Cited by 44 publications

References 9 publications

High resolution imaging of thin-film recording heads by superparamagnetic magnetic force microscopy tips

High resolution imaging of thin-film recording heads by superparamagnetic magnetic force microscopy tips

Low temperature force microscopy based on piezoresistive cantilevers operating at a higher flexural mode

Magnetic Force Microscopy — Towards Higher Resolution

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