Visualization of Magnetic Flux in Magnetic Materials and High Temperature Superconductors Using the Faraday Effect in Ferrimagnetic Garnet Films

Polyanskii, Anatolii; Cai, X. Y.; Larbalestier, D. C.

doi:10.1007/978-94-011-4493-3_33

Cited by 22 publications

(23 citation statements)

References 59 publications

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“…The MO experimental setup is described in Ref. [20]. We used a set of garnet MO indicator films of relatively large thickness of 5 µm made from (Bi,Lu) 3 (Fe,Ga) 5 O 12 with in-plane magnetization and different saturation fields 90 mT and 200 mT.…”

Section: Methodsmentioning

confidence: 99%

“…In this paper we report on a detailed MO investigation of a directly reacted MgB 2 sample which shows a rather uniform critical state, very unlike the percolative current flow revealed by MO imaging of high-T c superconductors [19][20][21]. Because the grain size is 3-5 µm is below the resolution limit of the MO technique, it is possible to further support the studies already cited [2][3][4]6,8,13] that conclude, by more indirect means, that grain boundaries are not weak links which cause electromagnetic granularity on more macroscopic scales.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magneto-optical studies of the uniform critical state in bulk MgB₂

Polyanskii¹,

Gurevich²,

Jiang³

et al. 2001

Supercond. Sci. Technol.

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We present a detailed magneto-optical investigation of the magnetic flux penetration in polycrystalline MgB 2 slabs made by direct reaction of B and Mg. Our results unambiguously indicate a uniform, Bean critical state magnetization behavior with almost no electromagnetic granularity. From the measured magnetic flux profiles we were able to extract the temperature dependence of the critical current density J c (T). The J c (T) value reaches 1.8×10 5 A/cm 2 at 10K and 0.12T, in good agreement with global magnetization measurements.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magneto-optical studies of the uniform critical state in bulk MgB₂

Polyanskii¹,

Gurevich²,

Jiang³

et al. 2001

Supercond. Sci. Technol.

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“…Magneto-optical (MO) method based on the Faraday effect have been used for the magnetic microstructure observation [8,9]. The angle of Faraday rotation of the polarization plane of the light is proportional to the component of local magnetic field in the direction of propagation of the light.…”

Section: Methodsmentioning

confidence: 99%

“…The angle of Faraday rotation of the polarization plane of the light is proportional to the component of local magnetic field in the direction of propagation of the light. Transparent magneto-optically active ferrite-garnet indicator films with in-plane anisotropy [9] was placed on the surface of the sample. The vector of magnetization of the indicator film rotates in the direction of the sample local magnetic field, producing a normal to the sample surface component of magnetization.…”

Section: Methodsmentioning

confidence: 99%

Large magnetic-field-induced strains in Ni-Mn-Ga alloys in rotating magnetic field

Sozinov¹,

Ezer²,

Kimmel

et al. 2001

J. Phys. IV France

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Abstract:A single-crystal samples of near-stoichiometric Ni 2 MnGa alloys with large magnetic field induced strain (MSM effect) at room temperature have been investigated. It was found that there is a reversible reorientation of easy magnetization direction and magnetic domain structure under applied magnetic field. By means of x-ray Laue diffraction method and difractometric analysis it was ascertained that these phenomena are connected with the growth of martensitic twin variant with the short crystallographic axis (c-axis) directed along the applied magnetic field. Furthermore, by means magneto-optical investigations we have found the correlation between martensitic microstructure and magnetic domain structure. The field-induced reorientation of martensite was able to change the dimensional lengths of the samples more than 4.5 %. 1.IntroductionMagnetic field control of the shape of ferromagnetic alloys with martensitic structure was suggested recently [1,2]. Such materials are highly beneficial for actuators [3,4]. Field-induced strains, larger than 4 %, have been observed in the single-crystal Ni2MnGa alloys [5,6]. There are no detailed studies concerning the martensitic microstructure changes connected with MSM (magnetic shape memory) effect. The aim of this work was to fill up this gap. 2.Experimental proceduresThe alloy Ni4g.7Mn3o.iGa2i.3 was melted in an induction furnace in argon atmosphere. The composition of the alloy was measured by wave-length dispersive spectroscopy (WDS). After homogenization at 1000 C during 3 days and aging at 800 C 1 day the alloy was air cooled to room temperature. X-ray diffraction measurements revealed the Heusler type ordered structure (L2y) for the alloy in austenitic state. Martensitic transformation points M s , Mf, A s , A/, and Curie point T c were measured using low field ac magnetic susceptibility technique (M,=29° C, M f = 26° C, A s = 32° C, A f = 35° C, T c = 99° C). Samples for magnetic investigation with dimensions of 4x4x4 mm were cut using spark cutting machine and one single Ni4s.7Mn30.1Ga21.3 grain.All the M-H curves were obtained by using a vibrating sample magnetometer (VSM). The specimen stage was mounted between the pole pieces of a 1 T electromagnet and could be rotated for different field orientations. In all measurements the rotation of the samples was carried out at zero magnetic field. Strains induced by magnetic field were measured by strain gauges. The rather large changes in the sample shape and size gave us the possibility to confirm the strain gauge data by micrometric measurements. Temperatures were carefully controlled with a temperature control unit, i.e. a large volume alcohol circulator.Back-reflection Laue technique was used to determine the change in an orientation of crystals. X-ray tube with W-anode was used. A low voltage level V = 12 kV (/ = 30 mA) was applied in order to avoid the characteristic line effect and to decrease the fluorescent radiation from sample. The distance between the film Article published online by EDP Sciences a...

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“…These merits suggest that the MOI technique can be very helpful to identify minerals carrying a magnetic moment in geological samples. The technique is, in fact, already widely used in material science for the observation of magnetic domain structures in magnetic materials [Polyanski et al, 1999;Welp et al, 2003] or flux penetration in superconductors [Dorosinskii et al, 1992;Jooss et al, 2002]. This technique has also been recently applied to geological samples [Bobyl et al, 2007].…”

Section: Introductionmentioning

confidence: 99%

Advances in magneto‐optical imaging applied to rock magnetism and paleomagnetism

Uehara

Beek

Gattacceca

et al. 2010

Geochem Geophys Geosyst

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[1] We present results of the magneto-optical imaging technique applied to rock samples. This technique measures the magnetic flux threading a magneto-optically active film, which rotates the polarization direction of transmitted light (Faraday rotation) and is directly placed on the sample. Through the analyzer of a reflected light microscope, the vertical component of the surface magnetic field of the sample is observed and can be quantified through a specific calibration procedure. Owing to the thin magneto-optically active film (5 mm) and the small sample-to-film distance (∼1 mm), stray fields produced by magnetic grains in rocks carrying saturation isothermal remanent magnetization are successfully imaged with a spatial resolution of 10 mm. We can also image the surface field distribution of rocks carrying natural remanent magnetizations by modulating the analyzer angle. In addition to its high spatial resolution, this technique offers a direct comparison between magnetic and reflected light images. Therefore, this new technique appears to be a powerful tool to map and identify the carriers of magnetic remanence in rock samples.

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Visualization of Magnetic Flux in Magnetic Materials and High Temperature Superconductors Using the Faraday Effect in Ferrimagnetic Garnet Films

Cited by 22 publications

References 59 publications

Magneto-optical studies of the uniform critical state in bulk MgB₂

Magneto-optical studies of the uniform critical state in bulk MgB₂

Large magnetic-field-induced strains in Ni-Mn-Ga alloys in rotating magnetic field

Advances in magneto‐optical imaging applied to rock magnetism and paleomagnetism

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Visualization of Magnetic Flux in Magnetic Materials and High Temperature Superconductors Using the Faraday Effect in Ferrimagnetic Garnet Films

Cited by 22 publications

References 59 publications

Magneto-optical studies of the uniform critical state in bulk MgB2

Magneto-optical studies of the uniform critical state in bulk MgB2

Large magnetic-field-induced strains in Ni-Mn-Ga alloys in rotating magnetic field

Advances in magneto‐optical imaging applied to rock magnetism and paleomagnetism

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Magneto-optical studies of the uniform critical state in bulk MgB₂

Magneto-optical studies of the uniform critical state in bulk MgB₂