Read Back Signals in Magnetic Recording - Research Group Fidler
Read Back Signals in Magnetic Recording - Research Group Fidler
Read Back Signals in Magnetic Recording - Research Group Fidler
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Abstract<br />
This thesis concentrates on calculat<strong>in</strong>g the read back signals of read heads, as used <strong>in</strong><br />
conventional hard disks. First the read back signal of a simplified 2-dimensional model is<br />
determ<strong>in</strong>ed by analytical means. Here the reciprocity pr<strong>in</strong>ciple is used.<br />
The ma<strong>in</strong> part of this work deals with the simulation of the read back process with the F<strong>in</strong>ite<br />
Element Method. The Landau-Lifshitz-Gilbert equation is solved, which describes the<br />
dynamic micromagnetic behavior of a magnetic model. To take effects of the sense current of<br />
the read head <strong>in</strong>to account, the current distribution for <strong>in</strong>homogeneous conductors has to be<br />
evaluated. Modern read heads use magnetoresistive effects. Thus the conductivities depend on<br />
the magnetization of the read head. The calculated current distribution generates a magnetic<br />
field, act<strong>in</strong>g on the magnetization of the read head itself. The programm<strong>in</strong>g and the<br />
implementation to make such simulations possible were the primary targets of this work.<br />
In the last part of this thesis the functionality of the program is tested with a simple 3dimensional<br />
model of a read head. The equilibrium state, the sensor curve, and the relaxation<br />
behavior are calculated. Moreover the <strong>in</strong>fluence of the magnetic shields is exam<strong>in</strong>ed. At last<br />
the read back signal is calculated for perfect transitions and for periodic bit patterns.<br />
This work resulted <strong>in</strong> a tool for simulat<strong>in</strong>g the whole read back process, which also allows the<br />
computer-based development of read heads. Furthermore the dynamic and static<br />
micromagnetic properties of read heads can be calculated.<br />
3