Crossover behavior in dynamics of frozen ferrofluids
Abbreviated Journal Title
J. Appl. Phys.
MAGNETIC PARTICLE SYSTEM; GLASSES; LIQUIDS; Physics, Applied
The imaginary part of susceptibility, chi", in frozen ferrofluids was measured as functions of temperature, frequency, and concentration of magnetic particles. In a very dilute region, where magnetic interaction is negligible, the relaxation time is mainly determined by Neel's relaxation in isolated particles and the frequency-dependent peak temperature in chi"(T), T-p, obeys the Arrhenius law. In the moderate concentration range, T-p has a Vogel-Fulcher (VF) relaxation with the measuring frequency. However, for concentration larger than a certain value, deviation from VF law occurs. Simulations show that the VF relation could be attributed to Ising spin-glass-like random and frustrated interaction between magnetic moments of particles. We suggest that particle configuration before freezing is critical to determine the distribution of pair exchange parameters. For high concentration, there are more ferromagnetic than antiferromagnetic bonds. The deviation from VF law at high concentration could be due to short range correlation among spins. (C) 2000 American Institute of Physics. [S0021- 8979(00)24908-6].
Journal of Applied Physics
Article; Proceedings Paper
"Crossover behavior in dynamics of frozen ferrofluids" (2000). Faculty Bibliography 2000s. 2509.