Abstract
The applicability of the strain-induced bcc phase of Co in magnetoresistive devices was studied. Ultrathin bcc Co(001) films and the influence of the additional layers needed for magnetoresistive devices were examined by means of /sup 59/Co nuclear magnetic resonance (NMR). NMR is shown to be a discriminating technique for determining the presence of structurally and magnetically pure bcc Co. The maximum stability for uncovered and Fe-covered layers grown on Fe(001)/GaAs(001) and Fe(001)/Ge(001) seed layers is found to be about 2 nm. Growth of an Al/sub 2/O/sub 3/ top layer preserves the bcc phase, in contrast to a Cu film which causes a transformation of the bcc structure to the fcc or the hcp phase. The bcc-preserving effects of Al/sub 2/O/sub 3/ imply the possibility to fabricate magnetic tunnel junctions with bcc Co(001) bottom electrodes. Although bcc Co is a force-induced structure, thin layers are shown to be stable over a few years when Al/sub 2/O/sub 3/ has been grown on top. Junction structures using bcc Co(001) bottom electrodes were grown and characterized
| Original language | English |
|---|---|
| Article number | 224430 |
| Pages (from-to) | 224430-1/10 |
| Journal | Physical Review B |
| Volume | 67 |
| Issue number | 22 |
| DOIs | |
| Publication status | Published - 2003 |