Multiple magnetic image reflection in perpendicular recording

Summary form only given. In a typical perpendicular system, writing is done by the trailing edge of the trailing pole (TP) of a single pole head (SPH). The recording field is controlled by the electrical current in a magnetizing coil. However, due to the use of a soft underlayer (SUL) there is an additional source of the magnetic flux, which indirectly contributes to the net recording field under the TP. Due to the multiple magnetic image reflection (MIR) effect, the magnetic flux can be extracted from the recording layer (RL) region under the leading pole (LP) and transferred to the region under the TP. It should be stressed that a DC-erased perpendicular medium in the presence of only one or no "mirrors" generates no stray field at all. The fact that a field of approximately 1.4 kOe can be extracted from a DC-erased medium, indicates that the MIR is clearly a multiplication process, in which the LP and SUL act as two magnetic "mirrors" that effectively displace the magnetic charges from the surfaces of the recording layer to "infinity." The intention of this paper is to theoretically and experimentally study in detail the consequences of the MIR on the recording characteristics of a recording system.