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要旨:
Spin freezing in the A-site spinel FeAl2O4, which is a spin-liquid
candidate, is studied using remnant magnetization and nonlinear magnetic
susceptibility and isofield cooling and heating protocols. The remnant
magnetization behavior of FeAl2O4 differs significantly from that of a
canonical spin glass, which is also supported by analysis of the
nonlinear magnetic susceptibility term chi(3)(T). Through the power-law
analysis of chi(3)(T), a spin-freezing temperature T-g = 11.4 +/- 0.9 K
and critical exponent gamma = 1.48 +/- 0.59 are obtained. A Cole-Cole
analysis of magnetic susceptibility shows the presence of broad spin
relaxation times in FeAl2O4, however, the irreversible dc susceptibility
plot discourages an interpretation based on conventional spin-glass
features. The magnetization measured using the
cooling-and-heating-in-unequal-fields protocol brings more insight into
the magnetic nature of this frustrated magnet and reveals unconventional
glassy behavior. Combining our results, we arrive at the conclusion that
the present sample of FeAl2O4 consists of a majority spin-liquid phase
with "glassy" regions embedded.
