Direct optical observation of ferromagnetic domains

Parpia, D. Y.; Tanner, B. K.; Lord, D. G.

doi:10.1038/303684a0

Cited by 26 publications

(4 citation statements)

References 5 publications

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“…Numerous references exist reporting the experimental observation of domain structure and behaviour by using a variety of techniques. Examples of different techniques can be found in Bitter (1931), Parpia, Tanner and Lord (1983), and Hetherington, Jakubovics, Szpunar and Tanner (1987). Excellent treatments of the whole subject of ferromagnetic domains are given by Kittel (1949) and Craik and Tebble (1965).…”

Section: Magnetic Domainsmentioning

confidence: 99%

The physical properties of magnetic inks

1993

NDT & E International

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source• a link is made to the metadata record in Durham E-Theses• the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. {Philip Larkin, Nursery Tale) IV AbstractThe magnetic particle inspection (MPI) method is a widely used non destructive testing (NDT) technique for ferrous structures. Magnetic inks used in MPI are suspensions of fine ferro/ferrimagnetic particles which, when applied to a magnetized test specimen, deUneate surface flaws. This work is an investigation of some of the properties of magnetic ink systems and some aspects of their interaction with defect leakage flux. Reviews of magnetism, the MPI method and leakage flux at defects are given. The construction, characterization and automation of a 1.2 T electromagnet vibrating sample magnetometer, used for magnetic measurements on the inks, is described. The instrument has a resolution of better than 10"'^ JT~^ A 20 model of indication formation in MPI, based upon the simulation of many particles in the neighbourhood of a defect, is presented. Results of the role of several of the model parameters are given. Results indicate that carrier coefficients of viscosity at the lower end of the range investigated (r/ = 0.3 mPas) are optimum. The size and contrast of an indication increases with defect size. The contrast and rate of formation of contrast increase with defect aspect ratio. The effect of the contrast paint layer thickness indicates that the recommendation of the British Standard, BS 5044 (1973), is qualitatively correct. Experimental observations of particles in field gradients reveals a discrepancy between theoretical and observed behaviour which is attributed, in particular, to unobservable voids in the particles. Detailed characterization of the particles shows them to be aggregates of 20 -200 nm crystallites which are probably single domain particles. The morphology of larger aggregates is related to measurements of the low field susceptibility Evidence from intensive magnetic measurements supports the relationship between magnetic properties and aggregate characteristics. A 'Int' magnetic viscosity effect is reported. At 77 K, the coeflScient of magnetic viscosity has a maximum near the coercivity field. A cknowledgementsIt is my privilege to acknowledge the assistance and support given to me by many people during the course of this work.

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Section: Magnetic Domainsmentioning

confidence: 99%

The physical properties of magnetic inks

1993

NDT & E International

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“…They usually form in the presence of a spontaneous symmetry breaking bifurcation [1], and are found in a variety of contexts, including magnetism [2], hydrodynamics [3], biology [4], Bose-Einstein condensates [5], and string theory [6]. The paradigmatic examples are the interfaces that separate domains with distinct magnetization in ferromagnetic materials [2,7], whose unique properties are exploited in modern spintronics devices to store or even transfer information [8]. Additionally, DWs are central to numerous phase transitions in condensed matter and quantum physics [4,9].…”

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Dissipative polarization domain walls in a passive driven Kerr resonator

Garbin,

Fatome,

Oppo

et al. 2020

Preprint

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“…We choose an (x, y) coordinate system with x along the tank and y in the transverse direction. The paddles are labeled by an integer j ∈ [1,10], and in the following y j indicates the transverse location of the center of the j-th paddle, assuming all of them located at x = 0. The time-dependent displacement of each paddle can be written in the form of a time-dependent amplitude a j (t) and a time-dependent phase φ j (t), η j (a j , y j ) = Re a j exp iφ j .…”

mentioning

confidence: 99%

“…They are of fundamental importance in many fields of modern physics. In wave dynamics, domain walls connecting neighbouring wave fields differing in wave amplitude and phase, are also called wave jumps [1][2][3].…”

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Phase Domain Walls in Weakly Nonlinear Deep Water Surface Gravity Waves

et al. 2018

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We report a theoretical derivation, an experimental observation and a numerical validation of nonlinear phase domain walls in weakly nonlinear deep water surface gravity waves. The domain walls presented are connecting homogeneous zones of weakly nonlinear plane Stokes waves of identical amplitude and wave vector but differences in phase. By exploiting symmetry transformations within the framework of the nonlinear Schrödinger equation we demonstrate the existence of exact analytical solutions representing such domain walls in the weakly nonlinear limit. The walls are in general oblique to the direction of the wave vector and stationary in moving reference frames. Experimental and numerical studies confirm and visualize the findings. Our present results demonstrate that nonlinear domain walls do exist in the weakly nonlinear regime of general systems exhibiting dispersive waves.

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Direct optical observation of ferromagnetic domains

Cited by 26 publications

References 5 publications

The physical properties of magnetic inks

The physical properties of magnetic inks

Dissipative polarization domain walls in a passive driven Kerr resonator

Phase Domain Walls in Weakly Nonlinear Deep Water Surface Gravity Waves

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