resumo
Giant magnetoimpedance (GMI) in the reentrant spin-glass (SG) phase of ferromagnetic Fe90Zr10 is reported. The temperature (T) dependence of the GMI allows the investigation of the spin dynamics in the SG phase in the MHz frequency regime and thus very short relaxation times tau (similar to 10(-8) s). The GMI shows a broad maximum around 150 K and diminishes with decreasing T below the glass temperature T-g of 15 K. The magnetic permeability data obtained from the GMI data show the general features observed in the ac magnetic susceptibility measured at lower frequencies (10 <= f <= 10(4) Hz), yielding values of T-f (=T-g(f)) that allow testing the validity of the power-law scaling used for describing the dynamics of SG-phases up to 15 MHz. A log-log plot of tau (=1/f) versus the reduced critical temperature shows two distinct regimes in the time-domain: (1) a critical slowing-down is observed for values tau > 3 x 10(-3) s; and (2) for 7 x 10(-8) <= tau <= 3 x 10(-3) s. In the latter case a fitting to the power-law yields the value 7.4 for the product of the critical exponents z nu, and 1.6 x 10(-7) s for the microscopic relaxation time tau(0). The product of the exponents is appropriate for an Ising spin glass. Published by AIP Publishing.
palavras-chave
RICH FE-ZR; GIANT MAGNETOIMPEDANCE; ELECTRICAL-RESISTIVITY; AMORPHOUS ALLOY; TRANSITION; TEMPERATURE; BEHAVIOR; MAGNETORESISTANCE; DEPENDENCE; FEXZN1-XF2
categoria
Physics
autores
Ribeiro, PRT; Ramirez, JMM; Vidyasagar, R; Machado, FLA; Rezende, SM; Dahlberg, ED
nossos autores
Reddithota Vidyasagar
Bolseiro de pós-Doutoramentoagradecimentos
This work was partially supported by the Brazilian Funding Agencies CNPq, CAPES, FACEPE, and FINEP, the American Physical Society, and DOE Award No. DE-SC0013599.