Spin-valve read heads with NiFe/Co90Fe10 layers for 5 Gbit/in2 density recording

Successful use of a NiFe/Co₉₀Fe₁₀ bilayer as a soft magnetic free layer in spin-valve films with a GMR enhanced structure comprised of NiFe/Co₉₀Fe₁₀/Cu/Co₉₀ Fe₁₀/FeMn is outlined. The GMR ratio of the spin-valve film with Co₉₀Fe₁₀ is over 7% and the coercivity of the free NiFe/Co₉₀Fe₁₀ bilayers is less than 5 Oe. A merged inductive/spin-valve head was fabricated with a read track-width of 1.3 μm and a read gap-length of 0.26 μm using spin-valve film with a Ta(50 Å)/NiFe(45 Å)/Co₉₀Fe ₁₀(30 Å)/Cu(32 Å)/Fe₁₀(22 Å)/FeMn(100 Å)/Ta(100 Å) structure and 260 Å thick domain control Co₇₈Cr₁₀Pt₁₂ magnet layers. Its read/write performance was tested on a low noise CoCr ₁₇Pt₅Ta₄ thin film disk with an Mr·t of 0.41 memu/cm² and a coercivity of 2500 Oe. There is no Barkhausen noise in the readback waveform. The result of the microtrack sensitivity profiles reveals an effective read track-width of 0.8 μm. A normalized output for a track-width of 880 μVpp/μm and D₅₀ of 166 kFCI was obtained. Using a PRML channel, a bit error rate of less than 10^-8 was obtained without error correction at a data rate of 3.3 MB/s and at a linear density of 217 kBPI on a thin film disk with an Mr·t of 0.72 memu/cm². Thus, 5 Gbit/in² density recording with a linear density of 217 kBPI and a track density of 23 kTPI is possible