Texture, strain and alloying in sputtered granular magnetic films

Franco, V.; Batlle, X.; Labarta, A.; Bassas, J.; Sandiumenge, F.

doi:10.1016/s1359-6454(98)00433-9

Cited by 9 publications

(17 citation statements)

References 15 publications

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“…Values for K within 0.30-0.40ϫ10 6 erg/cm 3 and ϭ0 for all as-deposited samples have been found, in agreement with the magnetoelastic energy calculation from the axial distortion. 21 Similar results have been observed in CoFe-Cu granular films, 26 though K values were smaller (ϳ0.2ϫ10 6 erg/cm 3 ), as a consequence of a lower degree of texture with respect to the CoFe-AgCu films.…”

Section: A Microstructure and Magnetic Anisotropysupporting

confidence: 77%

“…Fe and Cu were added to the widely studied Co-Ag system for a number of reasons: Fe was added to Co in order to increase the magnetic moment and, consequently, the magnetoresistive effect, 20 while a small amount of Cu ͑about 3% by volume͒ was added to increase the Co-Ag immiscibility. 21 Cu is immiscible in both Co and Ag, which leads to a granular system even for as-deposited samples, obviating substrate heating or postdeposition annealing, but not avoiding a certain degree of CoFeAgCu alloying. Postdeposition phase segregation was promoted by rapidly annealing ͑0.1 s͒ at 600, 650, 700, and 750°C.…”

Section: Methodsmentioning

confidence: 99%

“…A detailed description of the experimental procedure and structural characterization is given elsewhere. 21 Parallel and perpendicular hysteresis loops were measured with a vibrating sample magnetometer with fields up to 12 kOe, within 5 and 300 K. In-plane remanence curves ͑isothermal remanent magnetization and dc demagnetizing curves͒ were also measured at 5 K. The field sweeping rate was kept constant and all samples were carefully ac demagnetized before any experiments were performed in order to avoid magnetic-history dependence. Susceptibility measurements at low field were performed with a superconducting quantum interference device magnetometer, in the in-plane geometry.…”

Section: Methodsmentioning

confidence: 99%

“…21 Both CoFe and Ag crystals displayed a face-centered-cubic ͑fcc͒ structure with the ͗111͘ direction textured perpendicular to the film plane, with an angular dispersion for the CoFe particles of about 30°in as-deposited samples and about 10°in samples annealed at 750°C. Structural data also showed a rhombohedral distortion of the cubic cell in all as-deposited samples: The ͗111͘ direction is in compression, while the directions in the film plane are in tension, giving rise to a perpendicular uniaxial magnetic anisotropy along the textured ͗111͘ direction.…”

Section: A Microstructure and Magnetic Anisotropymentioning

confidence: 98%

“…Structural data also showed a rhombohedral distortion of the cubic cell in all as-deposited samples: The ͗111͘ direction is in compression, while the directions in the film plane are in tension, giving rise to a perpendicular uniaxial magnetic anisotropy along the textured ͗111͘ direction. 21 This axial distortion is associated with the residual stresses produced during deposition by differences in the thermal expansion coefficients of the substrate and the film. [22][23][24] The value of the perpendicular uniaxial anisotropy may be evaluated by comparing parallel and perpendicular hysteresis loops ͑Fig.…”

Section: A Microstructure and Magnetic Anisotropymentioning

confidence: 99%

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Remanence breakdown in granular alloys at magnetic percolation

Batlle

Franco

Labarta

et al. 2000

Journal of Applied Physics

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Microstructural effects on the magnetic behavior of rf-sputtered CoFe-AgCu granular alloys are examined through the study of the in-plane remanence-to-saturation magnetization ratio, M r /M s , as a function of temperature, ferromagnetic volume content, x v , and annealing temperature. At low ferromagnetic contents (x v р0.25), the M r M s ratio in as-deposited samples tends towards 0.5 at low temperature, as expected from the uniaxial perpendicular anisotropy displayed by all samples, which is magnetoelastic in nature and arises from the axial distortion of the CoFe face-centered-cubic cells. In as-deposited samples with x v Ͼ0.25 ͑well below the volume percolation threshold, x p ϳ0.5-0.55), a collective magnetic behavior develops due to magnetic correlations among particles. Consequently, a domain structure perpendicular to the film plane appears, which results in a remanence breakdown: M r /M s is about 0.2. Besides, magnetic correlations prevents the thermal decay of M r /M s , which is almost constant between 5 and 300 K, even for ferromagnetic particles no more than 3 nm in size. The axial distortion disappears with annealing, the cubic symmetry is recovered, the out-of-plane magnetic structure is lost and, therefore, the M r /M s ratio at low temperature tends towards 0.8 for highly annealed samples. Consequently, the magnetic properties of granular alloys depend on the interplay between anisotropy, exchange, and dipolar interactions, which in turn depend crucially on the microstructure.

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Section: A Microstructure and Magnetic Anisotropysupporting

confidence: 77%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: A Microstructure and Magnetic Anisotropymentioning

confidence: 98%