Spin valve heads with a corrosion resistant MnRh exchange layer

A new exchange material, Mn₇₈Rh₂₂, is described, requiring no post-deposition anneal to obtain the antiferromagnetic phase and leading to spin valve sensors with good corrosion resistance, thermal stability up to 225°C, and good exchange coupling characteristics. Potentiodynamic polarization scans performed in a sodium sulfate electrolyte show that Mn₇₈Rh ₂₂ films exhibit a good corrosion resistance, comparable to that of Ni₈₁Fe₁₉, Mn₈₀Ir₂₀, and Mn₅₀Ni₅₀ films but with higher corrosion potential. Spin valve structures prepared with this exchange material show an exchange coupling strength (J_ex) of 0.19 erg/cm² . The blocking temperature (T_B) of the as-deposited spin valve coupon samples is 235°C. Unshielded sensors with trackwidths W=4-6 μm and height h=1-2 μm were fabricated. The sensors show well-linearized magnetoresistance (MR) transfer curves, without hysteresis or Barkhausen noise and are thermally stable under consecutive 5 h anneals in vacuum up to 225°C. A shielded tape head device was fabricated showing a maximum output of 1.8 mV_pp/μm, with potential for operating at linear densities near 100 kfci, at which a 580 μV_pp/μm output is measured