Heusler alloy with insertion layer to reduce the ordering temperature for CPP, TMR, MRAM, and other spintronics applications

摘要

A spin valve structure is disclosed in which an AP1 layer and/or free layer are made of a laminated Heusler alloy having Al or FeCo insertion layers. The ordering temperature of a Heusler alloy such as Co₂MnSi is thereby lowered from about 350° C. to 280° C. which becomes practical for spintronics device applications. The insertion layer is 0.5 to 5 Angstroms thick and may also be Sn, Ge, Ga, Sb, or Cr. The AP1 layer or free layer can contain one or two additional FeCo layers to give a configuration represented by FeCo/[HA/IL]_nHA, [HA/IL]_nHA/FeCo, or FeCo/[HA/IL]_nHA/FeCo where n is an integer ≧1, HA is a Heusler alloy layer, and IL is an insertion layer. Optionally, a Heusler alloy insertion scheme is possible by doping Al or FeCo in the HA layer. For example, Co₂MnSi may be co-sputtered with an Al or FeCo target or with a Co₂MnAl or Co₂FeSi target.