Spin tunneling heads above 20 Gb/in/sup 2/

Spin tunneling recording heads above 20 Gb/in/sup 2/ have been fabricated using a bottom tunneling junction stack. The spin tunneling stack is made of Ta/PtMn/CoFe/Ru/CoFe/AlO/NiFe/Ta and stabilized by a permanent magnet abutted junction. The effective junction width is about 0.4 /spl mu/m wide and lapped to the junction with an optimum stripe height. The barrier has resistance area product of 15-20 /spl Omega//spl mu/m/sup 2/, leading to a typical head resistance of around 50 /spl Omega/. Isolated pulses during the spin-stand test shows large signal up to 10 mV. On track error rate floor is better than 10/sup -9/ and the head signal-to-noise ratio is also better than that of. a conventional spin valve GMR head. The areal density estimated (using BER of 10/sup -5/) is above 20 Gb/in/sup 2/.