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Characterization of magnetic materials by low-field microwave absorption techniques |
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| Authors: | R Valenzuela G Alvarez H Montiel MP Gutirrez ME Mata-Zamora F Barrn AY Snchez I Betancourt R Zamorano |
| Institution: | aDepartamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Mexico bDepartamento de Tecnociencias, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Mexico cDepartamento de Quimica Inorganica y Nuclear, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Mexico dDepartamento de Ciencia de Materiales, Instituto Politecnico Nacional, Mexico |
| Abstract: | A low-field non-resonant microwave absorption has recently been observed in a variety of magnetically ordered materials at low DC fields (−1000 Oe  HDC+1000 Oe), which is known as low-field microwave absorption (LFA). It has been shown that LFA is essentially similar to giant magnetoimpedance (GMI), and clearly different from ferromagnetic resonance (FMR). LFA strongly depends on the anisotropy field of the sample. In contrast with FMR (which can be described as the homogeneous precession of spins in the saturated state), LFA can be thought as a spin rotation process occurring during the magnetic saturation. In this work, we present a detailed study of the basic features of LFA in several types of materials: ferrites and amorphous microwires and ribbons; in particular the effects sample shape, temperature up to the Curie transition, the influence of easy axis and the effects of annealings. These examples show that once LFA is fully understood, it can become a powerful characterization tool. |
| Keywords: | Microwave absorption Ferromagnetic resonance Curie transition Anisotropy field |
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