Atomistic simulation of static magnetic properties of bit patterned media

• An atomistic model for bit patterned media is developed.
• Magnetic impurities between adjacent bits greatly affect the behavior of the material.
• A considerable amount of magnetic impurities can be tolerated in bit patterned media.
• A phase diagram of magnetic impurity concentration vs. temperature is presented.

In this work we present a new design of Co based bit pattern media with out-of-plane uni-axial anisotropy induced by interface effects. Our model features the inclusion of magnetic impurities in the non-magnetic matrix. After the material model was refined during three iterations using Monte Carlo simulations, further simulations were performed using an atomistic integrator of Landau–Lifshitz–Gilbert equation with Langevin dynamics to study the behavior of the system paying special attention to the super-paramagnetic limit. Our model system exhibits three magnetic phase transitions, one due to the magnetically doped matrix material and the weak magnetic interaction between the nano-structures in the system. The different magnetic phases of the system as well as the features of its phase diagram are explained.