Temperature-dependence of current-perpendicular-to-the-plane giant magnetoresistance spin-valves using Co{sub 2}(Mn{sub 1−x}Fe{sub x})Ge Heusler alloys

Journal Article · Thu Apr 21 00:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4947119· OSTI ID:22594616

Page, M. R.; Stewart, D. A.; York, B. R.; Read, J. C.; Choi, Y. -S.; Childress, J. R. ^[1]

---

1. San Jose Research Center, HGST, a Western Digital Company, 3403 Yerba Buena Road, San Jose, California 95135 (United States)

The properties of Co{sub 2}(Mn{sub 1−x}Fe{sub x})Ge (CMFG) (x = 0–0.4) Heusler alloy magnetic layers within polycrystalline current-perpendicular-to-the plane giant magnetoresistance (CPP-GMR) spin-valves are investigated. CMFG films annealed at 220–320 °C exhibit partly ordered B2 structure with an order parameter S{sub B2} = 0.3–0.4, and a lower S{sub B2} was found for a higher Fe content. Nevertheless, CPP-GMR spin-valve devices exhibit a relatively high magnetoresistance ratio of ∼13% and a magnetoresistance-area product (ΔRA) of ∼6 mΩ μm{sup 2} at room temperature, which is almost independent of the Fe content in the CMFG films. By contrast, at low temperatures, ΔRA clearly increases with higher Fe content, despite the lower B2 ordering for increasing the Fe content. Indeed, first-principles calculations reveal that the CMFG alloy with a partially disordered B2 structure has a greater density of d-state at the Fermi level in the minority band compared to the Fe-free (Co{sub 2}MnGe) alloy. This could explain the larger ΔRA measured on CMFG at low temperatures by assuming that s-d scattering mainly determines the spin asymmetry of resistivity as described in Mott's theory.

• OSTI ID: 22594616
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 15 Vol. 119; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
ASYMMETRY
COMPARATIVE EVALUATIONS
D STATES
DENSITY OF STATES
FERMI LEVEL
FILMS
HEUSLER ALLOYS
LAYERS
MAGNETORESISTANCE
ORDER PARAMETERS
POLYCRYSTALS
SCATTERING
SPIN
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
VALVES