Initial Permeability and Dynamic Response of FeCo Write Pole

In this work, the microstructure and the magnetostriction effect of the FeCo thin film are considered in micromagnetic simulations; therefore the magnetic properties of the FeCo thin film and write pole can be calculated more accurately. Based on the micromagnetic models, magnetic hysteresis loops of films are calculated. The simulation results show that the magnetostriction has great effect on the coercive force of FeCo films. Furthermore, the initial permeability and the dynamic response of the FeCo write pole are studied. When the easy axis of the write pole is along cross-track direction, a 128 nm-wide and 32 nm x 32 nm-ABS pole tip has a real initial permeability of 8.0 at low frequencies and a roll-off frequency of 5.0 GHz. The effect of the easy axis orientation is also studied. The write field is about 4300 Oe with a reversal time of approximately 0.15 ns. The scaling of the permeability is analyzed by a simple micromagnetic model without microstructure.