Demonstrating a tunneling magneto-resistive read head

We demonstrate the feasibility of a read head using a high-resistance spin- dependent tunneling (SDT) junction. The head consists of a 1.5 mum or 1.7 m um wide flux guide on top of the junction. The junction is about 0.8 mum wi de and varies in height. There is a pinned layer at the bottom of the stack . The tunnel barrier is made by plasma oxidation of about 10 Angstrom of al uminum. The barrier has resistance of about 3.7 k Omega mum(2), leading to a typical head resistance of a few k Omega. The heads are lapped to the edg e of the junction, and show 5% to 8 % TMR during transfer curve measurement . Isolated pulses during the spin stand test shows large signal up to 5.7 m V, We find a voltage sensing preamp is a better choice over a current sensi ng one.