Operation temperature ranges for ion-implanted bubble devices with 1 µm bubbles

Operation temperature ranges for He+ and H2+ ion-implanted bubble devices with 1 μm bubbles have been studied under a 100 kHz circular in-plane drive field condition. Samples are 4 Mb on-chip-cache bubble memory chips, which were fabricated on (YSmLuBiCa)3(FeGe)5O12LPE garnet films. For He+ implantation, the high temperature limit for the operation is restricted to 50°C at 1.2 eV/ųdamage level. On the other hand, for H2+ implantation, an operation temperature range, from 0°C to 95°C, has been obtained with more than 30 Oe bias field margin at 0.8 eV/ųdamage level. The maximum operation temperature linearly decreases with increasing lattice strain for both implantations. This results from Curie temperature decrease in the implanted layer with increasing lattice strain. However, 35°C difference in operation temperature range is found between He+ and H2+ implantation at the same lattice strain. There seems to be a local difference in magnetic characteristics between He+ and H2+ implanted layers.