Numerical optimization of writer and media for bit patterned magnetic recording

Abstract

In this work, we present a micromagnetic study of the performance potential of bit-patterned (BP) magnetic recording media via joint optimization of the design of the media and of the magnetic write heads. Because the design space is large and complex, we developed a novel computational framework suitable for parallel implementation on compute clusters. Our technique combines advanced global optimization algorithms and finite-element micromagnetic solvers. Targeting data bit densities of 4 Tb/in2, we optimize designs for centered, staggered, and shingled BP writing. The magnetization dynamics of the switching of the exchange-coupled composite BP islands of the media is treated micromagnetically. Our simulation framework takes into account not only the dynamics of on-track errors but also the thermally induced adjacent-track erasure. With co-optimized write heads, the results show superior performance of shingled BP magnetic recording where we identify two particular designs achieving write bit-error rates of 1.5×10−8 and 8.4×10−8, respectively. A detailed description of the key design features of these designs is provided and contrasted with centered and staggered BP designs which yielded write bit error rates of only 2.8×10−3 (centered design) and 1.7×10−2 (staggered design) even under optimized conditions.