Characteristics of the magnetosensitive non-resonant power absorption of microwave by magnetic materials

• Published in: Journal of alloys and compounds Vol. 369; no. 1; pp. 231 - 234
• Main Authors: Alvarez, G, Zamorano, R
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 28.04.2004; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cuprates superconductors (high tc and insulating parent compounds); Electron paramagnetic resonance; Electron paramagnetic resonance and relaxation; Exact sciences and technology; High- Tc superconductors; Magnetic measurements; Magnetic properties and materials; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Magnetically ordered materials; Microwave and radio-frequency interactions (excluding resonances); Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other interactions of matter with particles and radiation; Physics; Studies of specific magnetic materials; Superconductivity; Magnetic measurements; Electron paramagnetic resonance; High- T c superconductors; Magnetically ordered materials; Materials testing; Powders; Inorganic compounds; Crystal form; Cooling; Microwave radiation; Transition element compounds; Glass; Magnetic field effects; Low field; Liquid crystals; Heat treatments; Non destructive method; Microwave absorption; Barium oxides; High-Tc superconductors; Magnetic materials; Absorption spectra; Microwave spectra; Modulation spectroscopy; Quaternary compounds
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2003.09.058

By means of the modification of an electron paramagnetic resonance (EPR) spectrometer, two experimental techniques have been implemented to measure the magnetosensitive non-resonant absorption of microwaves (MANRAM): magnetically modulated microwave absorption spectroscopy (MAMMAS) and low field non-resonant microwave absorption spectroscopy (LFNORMAS). These techniques are proposed to be used in the characterization of magnetic materials at microwave frequencies. They are very sensitive, hence require very little amount of material for test in the form of crystals, glasses, powders, liquids; these wireless techniques are non-destructive. Magnetically modulated microwave absorption spectroscopy is carried out cooling or heating a sample under study in presence of a modulated magnetic field. The temperature of the material is taken and a graph of it versus the modulated absorption of microwaves is constructed. Low field non-resonant microwave absorption spectroscopy measures the magnetosensitive-modulated absorption of microwaves, by the material, with respect to cycled sweepings of an applied dc magnetic field. We present results for the ceramic superconductor YBa 2Cu 3O 7− x (YBCO), the antiferromagnetic (AF) MnO oxide and ferroelectromagnetic Pb(Fe 1/2Nb 1/2)O 3 (PFN). The absorption spectra are shown highlighting their main characteristics.