Seemann, K. M., Baltz, V., MacKenzie, M., Chapman, J. N., Hickey, B. J. and Marrows, C. H. (2007) Diffusive and ballistic current spin polarization in magnetron-sputtered L10-ordered epitaxial FePt. Physical Review B, 76(17), p. 174435. (doi: 10.1103/PhysRevB.76.174435)
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Publisher's URL: http://dx.doi.org/10.1103/PhysRevB.76.174435
Abstract
We report on the structural, magnetic, and electron transport properties of an L10-ordered epitaxial iron-platinum alloy layer fabricated by magnetron sputtering on a MgO (001) substrate. The film studied displayed a long-range chemical order parameter of S~0.90, and hence has a very strong perpendicular magnetic anisotropy. In the diffusive electron transport regime, for temperatures ranging from 2 to 258 K, we found hysteresis in the magnetoresistance mainly due to electron scattering from magnetic domain walls. At 2 K, we observed an overall domain wall magnetoresistance of about 0.5%. By evaluating the spin current asymmetry α=σ↑/σ↓, we were able to estimate the diffusive spin current polarization. At all temperatures ranging from 2 to 258 K, we found a diffusive spin current polarization of greater than 80%. To study the ballistic transport regime, we have performed point-contact Andreev-reflection measurements at 4.2 K. We obtained a value for the ballistic current spin polarization of ~42% (which compares very well with that of a polycrystalline thin film of elemental Fe). We attribute the discrepancy to a difference in the characteristic scattering times for oppositely spin-polarized electrons, such scattering times influencing the diffusive but not the ballistic current spin polarization.
| Item Type: | Articles |
|---|---|
| Keywords: | iron alloys, magnetic anisotropy, magnetic domain walls, magnetic epitaxial layers, magnetic hysteresis, magnetoresistance, metallic epitaxial layers, platinum alloys, point contacts, spin polarised transport, sputter deposition |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | MacKenzie, Dr Maureen and Chapman, Professor John |
| Authors: | Seemann, K. M., Baltz, V., MacKenzie, M., Chapman, J. N., Hickey, B. J., and Marrows, C. H. |
| Subjects: | Q Science > QC Physics |
| College/School: | College of Science and Engineering > School of Physics and Astronomy |
| Journal Name: | Physical Review B |
| Publisher: | American Physical Society |
| ISSN: | 1098-0121 |
| ISSN (Online): | 1550-235X |
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