Giant interface magnetostriction and temperature dependence in NiFe films encapsulated with Ta and Al/sub 2/O/sub 3/ layers

The interface magnetostriction (MS), /spl lambda//sub i/ of NiFe films (thicknesses:50 to 500 /spl Aring/) encapsulated with Ta and Al/sub 2/O/sub 3/ layers was studied in as-deposited and thermally annealed states. The MS of NiFe films encapsulated with only Ta (or Al/sub 2/O/sub 3/) layers increase (or decrease) rapidly with decreasing NiFe thickness, due to giant positive (or negative) /spl lambda//sub i/. The magnitudes of both positive and negative /spl lambda//sub i/ increase noticeably with processing at elevated temperatures. In structures containing Ta/NiFe and NiFe/Al/sub 2/O/sub 3/ interfaces, the total interfacial MS contribution is greatly reduced due to the opposite signs of /spl lambda//sub i/ at NiFe interfaces, leading to negligible thickness dependence of the effective MS in as-deposited and annealed states. The strong interfacial MS induced anisotropy affects markedly the uniaxial anisotropy of NiFe films for thicknesses below 100 /spl Aring/.