Papers by Keyword: Magnetic Relaxation

Abstract: sup>119Sn Mössbauer spectroscopy was used to study the transition from single-ion Kondo behavior in the magnetically ordered state in the heavy-fermion intermetallic СePdSn. Found that the temperature evolution of the experimental spectra agrees with the calculations within the two-level relaxation model. This allows one to treat magnetic structure of CePdSn as the decomposition of the total volume of the СePdSn sample into the antiferromagnetic domains. The temperature dependence of the frequency of fluctuations of the domains magnetization and the distribution density of itinerant electrons near the tin atoms in the process of RKKY interaction are investigated.

Abstract: Film composites based on magnetite Fe₃O₄ nanoparticles in the polyvinyl alcohol (PVA) matrix and the dried ferrofluid ARA-250 (Chemicell GmbH, Germany) were studied at temperatures 78-300 K by Mössbauer spectroscopy and magnetic measurements in magnetic fields H < 5 kOe. The Mössbauer spectra taken in magnetic fields show essential restoration of the magnetic hyperfine structure characteristic for the nanoparticles. The experimental Mössbauer spectra have been analyzed within the recently developed three-level [ and multi-level [ relaxation models of magnetic dynamics in an ensemble of single-domain particles. These models take into account the precession and diffusion of particles uniform magnetization as well as the particles size distribution and interparticle interactions.

Abstract: The electromagnetic wave absorption properties of amorphous alloy-epoxy composites have been investigated utilizing various amorphous alloy particle sizes in quasi-microwave frequency. The composite fabricated with small sized particle (< 26 μm) only revealed good absorption properties above 20dB with a thin thickness less than 6 mm. As particle size decreased, absorber had thinner matching thickness mainly due to increasing matching frequency. Such a variation of matching frequency was resulted from resonance frequency variation. The magnetic relaxation of the composites with small particle (< 38 μm) was contributed to magnetic resonance induced by demagnetization field. The eddy current also affected on the magnetic relaxation of the composites with large particle (> 38 μm) due to their large conductivity.