Abstract
Dynamical properties of the magnetic cluster compound were investigated. is taken to be representative of the class of trigonal and rhombohedral cluster compounds which were found to exhibit spin-glass behavior as measured by dc superconducting quantum interference device magnetometer and specific-heat measurements. These are examples of magnetic glassiness being observed in rare earth boron-rich crystalline cluster compounds. Well defined maxima in the in-phase linear ac susceptibility curves were observed, indicative of the spin-glass transition. Strong frequency dependence of the cusp temperature was found. The dependence of could not be analyzed satisfactorily by the dynamical scaling theory of a three-dimensional spin glass. A more detailed investigation of the behavior of relaxation times by Cole-Cole analysis showed that the behavior in is different from the simple blocking of a superparamagnetic system, because of the temperature dependence of the parameter representing the width of the relaxation-time distribution function The median relaxation time was also determined and the data were found to be described well in terms of a generalized Arrhenius law These results indicate that is a two-dimensional spin-glass system, which supports what has been speculated previously.
- Received 26 March 2003
DOI:https://doi.org/10.1103/PhysRevB.68.214422
©2003 American Physical Society