Influence of hard bubble suppression layer on gate operation in Bloch line memory

It is thought that a hard bubble suppression (HBS) layer, which is formed in the path on which magnetic bubbles are propagated in a Bloch line (BL) memory, may have some influence on the gate operation. This influence has been investigated experimentally. We have verified that two types of BLs exist in the HBS area. One type of BL has a Bloch point (BP) in it. The other type of BL has no BP. These two types are classified by the relationship between the magnetization in the HBS area and the magnetization in the BL. The BL with the magnetization antiparallel to the magnetization in the HBS layer has a BP in it, but the BL with the magnetization parallel to the magnetization in the HBS layer has no BP. We have also confirmed that BLs are annihilated when a stripe domain head is shrunk from the HBS area to the non-HBS area. This annihilation depends on the rise time of the pulsed field for shrink and the value of the in-plane field along the long axis of the stripe domain. The BL annihilation during the gate operation in the HBS area cannot be prevented in any field conditions of the practical devices. The stripe domain head should therefore be prevented from going into the HBS area during the gate operation.