The (Anomalous) Hall Magnetometer as an Analysis Tool for High Density Recording Media

Haan, S. de; Lodder, Cock; Popma, T.J.A.

doi:10.3379/jmsjmag.15.s2_349

Cited by 27 publications

(17 citation statements)

References 16 publications

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“…Given 10 GBits/in 2 (expected in the year 2000) the fundamental structural dimensions (crystal size and surface topology), intrinsic magnetic structures (domains) and the bit dimensions are approaching similar sizes. Research was started in the author's laboratory in three complementary areas: (a) investigation into the relation between shape and magnetic behaviour in artificially etched 'bits' [38], (b) measurement and micromagnetic modelling of the switching behaviour of individual magnetic entities in sub-micron Hall-crosses [39], and (c) observation of microstructure and written bits by AFM and MFM [40,41]. These mesoscopic measurements serve as an input for micromagnetic simulations [42,43].…”

Section: Macro-meso-micro Magnetic Propertiesmentioning

confidence: 99%

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Magnetic structures in CoCr media for perpendicular magnetic recording

Lodder

1996

Journal of Magnetism and Magnetic Materials

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High bit densities have been demonstrated in longitudinal as well as in perpendicular magnetic recording. For the latter an area density of more than 12 Gbit/in 2 has been obtained in a sputtered Co-Cr-Ta hard disk with a soft magnetic underlayer recorded with a special single pole head. In this paper the role of microstructure and morphology in relation to the compositional separation is discussed. Very sensitive anomalous Hall measurements have been performed from submicron Co-Cr samples to obtain more detail information about the reversal characteristics of the material. The results obtained have been used in our model for micromagnetic simulations. One of the conclusions is that most of the magnetic entities reversing their magnetisations are much smaller than the volume of one Co-Cr column.

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Section: Macro-meso-micro Magnetic Propertiesmentioning

confidence: 99%

“…In order to study the reversal mechanism in more detail the hysteresis loop of sub-micron dimensions of Co-Cr samples was determined with the so-called Anomalous Hall Effect (AHE) [39]. Various Co-Cr samples were measured [45].…”

Section: Anomalous Hall Effect Measurementsmentioning

confidence: 99%

Magnetic structures in CoCr media for perpendicular magnetic recording

Lodder

1996

Journal of Magnetism and Magnetic Materials

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“…is severely limited by the number of Co-Cr columns which can be simulated. The 'meso' -magnetic behaviour of the samples is studied by using a very sensitive technique: the anomalous Hall effect (AHE) applied on submicron Hallcrosses [20]. This technique offers us the possibility to bridge the gap between the macro magnetic and the micromagnetic behaviour responsible for the reversal mechanism.…”

Section: Macro-me So-micro Magnetic Propertiesmentioning

confidence: 99%

“…The maximum sensitivity of a commercial VSM is typical in the order of 10-7 kAhn, whereas the magnetic moment involved in the switching of one Co-Cr column is in the order of [10][11][12] kAlm. With A description of the anomalous Hall measurement set-up is given in [20]. Figure 6 shows a drawing of the Hall cross with a limited number of columns inside the measured area.…”

Section: Anomalous Hall Measurements On Sub-micron Samplesmentioning

confidence: 99%

Magnetic microstructures in Co-Cr sputtered thin films for perpendicular recording

Lodder

Haan

1997

J. Magn. Soc. Jpn.

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Abstract-The relation between deposition parameters, microstructural and magnetic properties are influencing the reversal mechanism of sputtered Co-Cr thin films having perpendicular anisotropy. Three Co-Cr films with perpendicular coercivities (Hu) of 11, 90 and 170 kAlm are investigated.Besides the Hc.l seveml other parameters were studied by VSM, SEM, NMR, MFM, AFM, selective etching, such as the Hufl\ , Cr-segregation, domain structure, column sizes, etc.The anomalous Hall effect (AHE) has been used to record the hysteresis curves of sub-micron Hall crosses. This very sensitive technique in combination with e-beam lithography and ion-beam etching resulted in the recording of AHE hysteresis loops with dimensions of the Hall crosses as small as 0.3 x 0.3 J.Ul1 2 • The AHE-loops of three samples, with less than 60 columns, show ditT.erent magnetic properties and the total number of steps measured in the hysteresis loop was 5 times the number of columns. The different reversal mechanism observed by the AHE are related to differences in microstructure, coercivity and domain size. The analysis of AHE hysteresis loops we conclude that magnetic units on the limit of superparamagnetism could be present in Co-Cr. The obtained results have been used as input for our model for micromagnetic simulations. Micromagnetic simulations shows that the initial layer and the exchange coupling of the initial layer with the columns has a large effect on the magnetisation reversal processes in the film.

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“…The anomalous Hall-effect magnetometer (AHM) is used to measure hysteresis loops from an area of 200 × 200 nm of a Co-Cr film [3]. Simulations of a cluster of Co-Cr particles are useful in interpreting these measurements and obtain a better understanding of the reversal process in Co-Cr films.…”

Section: Introductionmentioning

confidence: 99%