Vertical Bloch line memory: state of the art and future prospect

The micromagnetically based vertical Bloch line memory (VBLM) represents the only monolithic memory concept allowing for storage densities in excess of several 100 Mb/cm². In conventional bubble memories, the presence or absence of vertical Bloch line pairs (VBLs) having the same chirality serves as the binary information. The current status of related research is reviewed, focusing on theoretical and experimental aspects of VBL injection either in stripe-domain heads or at the side flank walls (write function), local-stripe-domain and VBL stabilization, VBL propagation either by current or field access, and detection (read function). These individual device functions are discussed in the light of VBL stability estimates complemented by the most promising technical approaches. The design and expected performance data of a future 64 Mb VBLM currently under development at Wuppertal University are presented and discussed