He-RBS, He-ERDA and heavy ion-ERDA analysis of Si/Ta 70Å/CoFe 35Å/ HfAlO /CoFe 35Å/Ta 30Å systems


He-RBS, He-ERDA and heavy ion-ERDA analysis of Si/Ta 70Å/CoFe 35Å/ HfAlO /CoFe 35Å/Ta 30Å systems

Barradas, N. P.; Matias, V.; Sequeira, A. D.; Soares, J. C.; Kreissig, U.; Wang, J. U.; Freitas, P. P.

Low resistance spin-dependent tunnel junctions are investigated for read-head applications due to their large tunneling magnetoresistance effect and low junction resistance-area product. Typical full junction structures can be Ta 70Å/NiFe 70Å/MnIr 80Å/CoFe 35Å/Hf(x)Al(y)O(z) t/CoFe 35Å/NiFe 40Å/Ta 30Å, with t around 10 Å, annealed to temperatures up to 250ºC. We analysed simpler structures with RBS experiments at a grazing angle of incidence in order to study the junction only. Heavy ion- and He-ERDA experiments were also done. The composition of the HfAlO barrier is determined, showing that a slightly substoichiometric oxide is formed. On annealing at 240ºC, the interfaces of the barrier become sharper. TEM results confirm that the barrier is continuous after annealing. This is related to an increase in the tunnel magnetoresistance signal from 4% to 13.5% after annealing.

Keywords: RBS; ERDA; tunnel junctions; magnetoresistive materials

  • Nuclear Instruments and Methods in Physics Research B 219-220(2004), 742-746

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Publ.-Id: 7117