Angular Dependence of Coercivity and Bit Error Rate Estimation for Shingled Magnetic Recording With ECC Media

Abstract

Shingled magnetic recording (SMR) with exchange-coupled composite media provides a feasible way by enhancing the writing capability and reducing the media switching field for achieving ultrahigh areal density of magnetic storage. However, the media switching field is dependent on the angle between the easy axis and the applied field. The adjacent track encroachment induced by this angular disturbance may happen, which could increase recording noise and lead to measurable erasure. This problem is highlighted in SMR system because of the enlarged stray field. A trapezoidal shingled writing head is modeled to explore the spatial field distribution and how the writing performance is affected by the angular dependence of media coercivity. The results show that a larger easy axis deviation and a smaller anisotropy energy density ratio of hard region will be helpful for reducing switching field to improve writing capability. The analysis also suggests that, if properly arranged, the adjacent bits can suffer minimized encroachment caused by variation of angularly induced switching field and attain a satisfactory bit error rate of as low as <5×10 −4 .Index Terms-Bit error rate (BER), coercivity, exchange-coupled composite (ECC), shingled magnetic recording (SMR), switching field.