Nanocrystalline Sm-(Co,Cu,Ni) Films with Giant Coercivity
Abstract
The drive for higher density recording media calls for new materials with smaller grain size (<100 ; Åand higher coercivity, in the range of 3-4 kOe. Rare earth intermetallic compounds appear to be suitable for this application. Several studies have already been reported in Sm-Co thin films. In this work, we have studied the magnetic and structural properties of sputtered Sm-(Co,Cu,Ni)/Cr bilayers. The as-deposited films were amorphous and relatively soft with a coercivity around 100 Oe. A nanocrystalline structure was developed after annealing giving rise to a huge enhancement in coercivity. The maximum coercivity of 42 kOe was obtained in a SmCo_2Cu3 sample annealed for 30 min. at 550^circ C . Magnetic viscosity measurements showed that the switching volume is of the same order as the crystallite size. Remanence measurements showed that interparticulate interactions are magnetizing and rather independent of the crystallization stage. These data indicate that the huge coercivity enhancement is due to the domain walls pinning at the high anisotropy Sm-Co precipitates. The possibility of tuning the coercivity more than two orders of magnitude by varying the annealing conditions makes this type of thin films suitable for a wide variety of applications, from longitudinal recording media to thin film permanent magnets.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 1998
- Bibcode:
- 1998APS..MAR.U1610H