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Magnetic and Spintronic Materials and Their Applications
Published in Song Sun, Wei Tan, Su-Huai Wei, Emergent Micro- and Nanomaterials for Optical, Infrared, and Terahertz Applications, 2023
Magneto-optic effect. Magneto-optic effect refers to physical interaction between magneticmaterials (or materials in magnetic field) and light. Magneto-optic effect in magnetic materials mainly includes Faraday effect, magneto-optic Kerr effect (MOKE), Cotton-Mouton effect, and Voigt effect. Faraday effect depicts the light polarization rotation when a light through a material under a magnetic field which is applied in the direction of light propagation. MOKE describes the polarization changes when a linearly polarized light reflected from magnetic (or spintronic) materials. Cotton-Mouton effect and Voigt effect are both magneto-birefringence effects, in which the birefringence occurs when a magnetic field is applied perpendicular to the direction of light propagation. Due to magneto-optic effect, the magnetic materials can modulate and manipulate the properties of light, such as amplitude, phase, polarization, and spectrum.
Examples of the Design of Measurement Systems
Published in Robert B. Northrop, Introduction to Instrumentation and Measurements, 2018
To make an electronic polarimeter, we need an electrical means of nulling the polarimeter output, as opposed to physically rotating P2 around the z-axis. One means of generating an electrically controlled optical rotation is to use the Faraday magneto-optic effect. Figure 13.3 illustrates a FR. A FR has two major components: (1) a core of a transparent, magneto-optically active medium (many transparent gasses, liquids, and solids exhibit magneto-optic activity; for example, a lead glass rod with optically flat ends or a glass test chamber with optically flat ends containing a gas or liquid can be used); and (2) a solenoid coil wound around the rod or test chamber (core) that generates an axial magnetic field, B, inside the rod or chamber collinear with the entering LPL beam. The exiting LPL beam undergoes optical rotation according to the simple Faraday relation (Hecht 1987): () θm=V(λ,T)B¯zl,
Anisotropic Materials
Published in Daniel Malacara-Hernández, Brian J. Thompson, Advanced Optical Instruments and Techniques, 2017
A table of Verdet constants for some common materials is given in Table 20.7. The material that is often used in commercial magneto-optic-based devices is some formulation of iron garnet. Data tabulations for metals, glasses, and crystals, including many iron garnet compositions, can be found in Chen [22]. The magneto-optic effect is the basis for magneto-optic memory devices, optical isolators, and spatial light modulators [23,24].
Investigation of the magnetic field sensing properties of a magnetic fluid clad microfiber knot sensor
Published in Instrumentation Science & Technology, 2019
The magnetic fluid is a highly stable colloidal suspension with single-domain ferromagnetic nanoparticles evenly distributed throughout a suitable carrier liquid. Magnetic fluid possesses both the fluidity of liquid and the magnetism of solid magnetic material. It has been reported that the originally dispersed magnetic particles in magnetic fluids agglomerate into ordered magnetic columns in the presence of an external magnetic field.[1–4] The stronger the field, the more columns formed. In this process, the refractive index and light transmission of the magnetic fluid varied with the externally applied magnetic field, which is usually called the magneto-optic effect.