Frequency dependence of the spin glass freezing temperatures in icosahedral R–Mg–Zn (R = rare earth) quasicrystals

Abstract

We present ac susceptibility measurements with the frequency spanning three orders of magnitude on single grain, icosahedral R–Mg–Zn (R = rare earth) quasicrystals. The freezing temperature in Gd-based, Heisenberg spin glasses in this family increases by ∼2% with a frequency increase from 10 Hz to 10 kHz, whereas the freezing temperature in the non-Heisenberg members of the family is significantly more responsive to the frequency change (by 16–22%), suggesting that an additional magnetic anisotropy distribution in the non-Heisenberg spin glasses causes changes in the low frequency magnetic dynamics.

Keywords:

• spin glass
• quasicrystals
• freezing temperature
• frequency dependence

Acknowledgments

The help of I.R. Fisher, A.F. Panchula and K.O. Cheon in sample synthesis and decadal room temperature annealing studies is greatly appreciated. Work at the Ames Laboratory was supported by the Department of Energy, Basic Energy Sciences, Division of Materials Sciences and Engineering, under Contract No. DE-AC02-07CH11358. S.L.B. acknowledges partial support from the State of Iowa through Iowa State University.