Perpendicular magnetic anisotropy and high spin-polarization ratio in epitaxial Fe-N thin films

Nian Ji, M. S. Osofsky, Valeria Lauter, Lawrence F. Allard, Xuan Li, Kevin L. Jensen, Hailemariam Ambaye, Edgar Lara-Curzio, Jian Ping Wang

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54 Scopus citations

Abstract

We have demonstrated a general framework for realizing and modulating perpendicular magnetic anisotropy in a rare-earth-element and heavy-metal-free material system. Using GaAs(001)/Fe(001) template, we have developed a synthesis scheme to produce epitaxial body center tetragonal Fe-N with (001) texture. By varying the N doping concentration, the crystal tetragonality (c/a) can be tuned in a relatively wide range. It is found that the Fe-N layer developed a strong perpendicular magnetic crystalline anisotropy (MCA) as it approaches the iron nitride interstitial solubility limit. Further annealing significantly improves the MCA due to the formation of chemically ordered Fe 16N 2. In addition to realizing an MCA up to 107 erg/cm3, the spin polarization ratio (P ∼ 0.52), as probed directly by a point-contact Andreev reflection (PCAR) method, even shows a moderate increase in comparison with normal metal Fe (P ∼ 0.45). These combined properties make this material system a promising candidate for applications in spintronic devices and also potential rare-earth-element free magnets.

Original languageEnglish (US)
Article number245310
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume84
Issue number24
DOIs
StatePublished - Dec 14 2011

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