Effects of deposition process parameters on exchange coupling of α-Fe/sub 2/O/sub 3//NiFe bi-layers and GMR of α-Fe/sub 2/O/sub 3//NiFe/Cu/NiFe spin valves

Abstract

Effects of deposition process parameters on the exchange coupling of /spl alpha/-Fe/sub 2/O/sub 3//NiFe bi-layers and GMR characteristics of /spl alpha/-Fe/sub 2/O/sub 3//NiFe/Cu/NiFe spin-valves using optimized anti-ferromagnetic /spl alpha/-Fe/sub 2/O/sub 3/ layer have been investigated. The exchange bias field was increased in /spl alpha/-Fe/sub 2/O/sub 3/(50 nm)/NiFe (7 nm) bi-layers by increasing oxygen partial pressure to 14.7%, substrate bias to 125 V, and input sputtering power up to 800 W of RF reactively sputtered /spl alpha/-Fe/sub 2/O/sub 3/ films. The thickness of NiFe and /spl alpha/-Fe/sub 2/O/sub 3/ layers also had an influence on the exchange coupling characteristics. By decreasing NiFe thickness from 35 nm to 5 nm and increasing /spl alpha/-Fe/sub 2/O/sub 3/ thickness from 550 nm, the exchange bias field dramatically increased up to 62.5 Oe. However, in the /spl alpha/-Fe/sub 2/O/sub 3/ thickness range of 50-100 nm, the exchange bias field decreased from 62.5 to 21.5 Oe. The GMR performance of as-deposited Si//spl alpha/-Fe/sub 2/O/sub 3/(50 nm)/NiFe(3.25 nm)/Cu(2 nm)/NiFe(3.25 nm)/Au (5.4 nm) spin valve structures was characterized. The CMR ratio and MR sensitivity was 5.2% and 0.6%/0e, respectively.