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

Operation temperature ranges for He+ and H
2
+ 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)
5
O
12
LPE garnet films. For He+ implantation, the high temperature limit for the operation is restricted to 50°C at 1.2 eV/Å
³
damage level. On the other hand, for H
2
+ 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/Å
³
damage 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 H
2
+ implantation at the same lattice strain. There seems to be a local difference in magnetic characteristics between He+ and H
2
+ implanted layers.