Magnetically Glassy Phase in Mechanically-Milled GdAl_2
Abstract
The ac susceptibility of mechanically-milled GdAl2 was measured. The behavior of the susceptibility for samples that were milled for 350 h and 590 h were compared. The measurements were made after cooling in zero field. Various dc fields were applied as the data were taken upon warming. The ac data are consistent with dc magnetization data, showing anomalies at a temperature in the vicinity of the bulk crystalline GdAl2 paramagnetic (PM) to ferromagnetic (FM) transition. The onset of the magnetically glassy phase was signaled by a broad peak at a lower temperature (T ≈ 50 K). The shift in the temperature of the peak with frequency that is usually seen in magnetically glassy and superparamagnetic systems was virtually undetectable in the range of frequencies used (10 1000 Hz). An applied dc bias field suppresses the ac susceptibility in the region of the PM-FM transition and sharpens the glassy peak for small bias fields. However, the shift in the peak with frequency remained extremely weak. The behavior may be interpreted in terms of strongly interacting grains of disordered GdAl_2. Research was supported by NSF DMR-9875425 and UNI Department of Physics.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARY23009S