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Title: High spin polarization in epitaxial Fe4N thin films using Cr and Ag as buffer layers

Journal Article · · Applied Physics Letters
DOI: https://doi.org/10.1063/1.5023698 · OSTI ID:1503634

Fe4N thin films with (001) texture were prepared by reactive sputtering on MgO substrates, utilizing either a Cr or Ag buffer layer to facilitate the epitaxial growth. X-ray diffraction, atomic force microscopy, and vibrating sample magnetometry measurements show that the Fe4N thin film grown on the Ag buffer layer is superior to that grown on the Cr buffer layer. The point contact Andreev reflection measurement was then conducted, and the spin polarizations were determined to be 61.1% and 81.3% for Fe4N thin films with Cr and Ag buffer layers, respectively. The 81.3% spin polarization is significantly higher than the ratio reported previously for Fe4N and is comparable with that of state-of-the-art Heusler alloys. This result is in agreement with the theoretical prediction on the discrepancy between the two differently defined spin polarizations for Fe4N. Moreover, our study indicates that an optimized growth process for Fe4N thin films is crucial for achieving a high spin polarization and that true half-metallicity could potentially be realized with Fe4N. Furthermore the high spin polarization of Fe4N combined with its low fabrication temperature and simple composition makes Fe4N a competitive candidate to be a half-metallic ferromagnet in spintronic devices.

Research Organization:
Energy Frontier Research Centers (EFRC) (United States). Spins and Heat in Nanoscale Electronic Systems (SHINES); Univ. of California, Riverside, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
SC0012670
OSTI ID:
1503634
Alternate ID(s):
OSTI ID: 1433574
Journal Information:
Applied Physics Letters, Vol. 112, Issue 16; ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 18 works
Citation information provided by
Web of Science

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Cited By (3)

Strain relaxation in epitaxial γ ′-Fe 4 N ultrathin films journal September 2019
Effect of interfacial interdiffusion on magnetism in epitaxial Fe 4 N films on LaAlO 3 substrates journal November 2019
In-situ growth of iron mononitride thin films studied using x-ray absorption spectroscopy and nuclear resonant scattering text January 2019

Figures / Tables (5)