Effect of Ta underlayer on the magnetic properties of sputter-prepared NiFe(5 nm)/FeMn(20 nm) bilayer films have been studied. The magnetic properties of studied films are optimized by modification of working Ar pressure deposition of Ta (PTa) in the range of 2–12 mTorr and thickness of Ta (tTa) in the range of 0–25 nm. X-ray diffraction results show that the crystallinity of the FeMn(111) strongly depends on the PTa and tTa. All studied films exhibit smooth and flat surface with root-mean-square roughness below 1 nm due to deposition at RT. Large EB field (Heb) of 65–123 Oe with small coercivity (Hc) of 5–16 Oe is obtained. Besides, the change of Heb with various PTa and tTa are related to the crystallinity of FeMn(111) layer, interfacial roughness, and also strain/stress. Correlation between magnetic properties and microstructure is also discussed. This study suggests that proper Ta underlayer is crucial in the exchange bias for NiFe/FeMn bilayer system.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry