GROWTH and DEPTH-DEPENDENCE of SATURATION MAGNETIZATION of IRON NITRIDE THIN FILMS on MgO SUBSTRATE

Nian Ji; Valeria Lauter; Hailemariam Ambaye; Jian Ping Wang

doi:10.1142/S201032471250004X

GROWTH and DEPTH-DEPENDENCE of SATURATION MAGNETIZATION of IRON NITRIDE THIN FILMS on MgO SUBSTRATE

Nian Ji, Valeria Lauter, Hailemariam Ambaye, Jian Ping Wang

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

We used polarized neutron reflectometry (PNR) to investigate the depth-dependent saturation magnetization (4πM_s) of bi-layer structured Fe-N/Fe grown on MgO substrates, which were prepared by a facing target sputtering method followed by a subsequent annealing process to purposely study the N inter-diffusive effect. It is observed that by tuning the Fe layer thickness from 2 nm to 5 nm, the magnetic properties of the resulting product varies substantially. According to X-ray diffraction, an additional peak, indexed to Fe₁₆N₂ (004), was developed in the sample with thinner (2 nm) underlayer. Its corresponding PNR study shows a 4πM_s of up to 2.82 T towards the substrate interface, which is 14% higher than the known limit (Fe₆₅Co₃₅ ∼ 4πM_s = 2.45 T). We attribute this giant magnetization to the presence of chemically ordered Fe₁N₂. We have seen evidence that the high M_s is favorably stabilized due to the lattice misfit. The thickness range is consistent with the strained region of the films. This depth-dependent saturation magnetization analysis can shed a light to help understand the previous magnetization reports by classical magnetometry methods for the samples prepared using the same underlayer.

Original language	English
Article number	1250004
Journal	SPIN
Volume	2
Issue number	1
DOIs	https://doi.org/10.1142/S201032471250004X
State	Published - Mar 1 2012
Externally published	Yes

Funding

The work done at SNS and ORNL are sponsored by U.S. Department of Energy, O±ce of Basic Energy Sciences under No. DE-AC02-98CH10886. Characterization carried out at the Characterization Facility, UMN receives support from the NSF through the NNIN and MRSEC program (Grant No. DMR-0819885). The work done at SNS and ORNL are sponsored by U.S. Department of Energy, Office of Basic Energy Sciences under No. DE-AC02-98CH10886. Characterization carried out at the Characterization Facility, UMN receives support from the NSF through the NNIN and MRSEC program (Grant No. DMR-0819885).

Funders	Funder number
Office of Basic Energy Sciences	DE-AC02-98CH10886
National Science Foundation
U.S. Department of Energy
National Sleep Foundation	DMR-0819885
Basic Energy Sciences
Oak Ridge National Laboratory
Materials Research Science and Engineering Center, Harvard University

Keywords

FeN
FeN
facing target sputtering
giant saturation magnetization
iron nitride
polarized neutron reflectometry

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title = "GROWTH and DEPTH-DEPENDENCE of SATURATION MAGNETIZATION of IRON NITRIDE THIN FILMS on MgO SUBSTRATE",

abstract = "We used polarized neutron reflectometry (PNR) to investigate the depth-dependent saturation magnetization (4πMs) of bi-layer structured Fe-N/Fe grown on MgO substrates, which were prepared by a facing target sputtering method followed by a subsequent annealing process to purposely study the N inter-diffusive effect. It is observed that by tuning the Fe layer thickness from 2 nm to 5 nm, the magnetic properties of the resulting product varies substantially. According to X-ray diffraction, an additional peak, indexed to Fe16N2 (004), was developed in the sample with thinner (2 nm) underlayer. Its corresponding PNR study shows a 4πMs of up to 2.82 T towards the substrate interface, which is 14% higher than the known limit (Fe65Co35 ∼ 4πMs = 2.45 T). We attribute this giant magnetization to the presence of chemically ordered Fe1N2. We have seen evidence that the high Ms is favorably stabilized due to the lattice misfit. The thickness range is consistent with the strained region of the films. This depth-dependent saturation magnetization analysis can shed a light to help understand the previous magnetization reports by classical magnetometry methods for the samples prepared using the same underlayer.",

keywords = "FeN, FeN, facing target sputtering, giant saturation magnetization, iron nitride, polarized neutron reflectometry",

author = "Nian Ji and Valeria Lauter and Hailemariam Ambaye and Wang, {Jian Ping}",

note = "Publisher Copyright: {\textcopyright} 2012 World Scientific Publishing Company.",

year = "2012",

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doi = "10.1142/S201032471250004X",

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AU - Ji, Nian

AU - Lauter, Valeria

AU - Ambaye, Hailemariam

AU - Wang, Jian Ping

PY - 2012/3/1

Y1 - 2012/3/1

N2 - We used polarized neutron reflectometry (PNR) to investigate the depth-dependent saturation magnetization (4πMs) of bi-layer structured Fe-N/Fe grown on MgO substrates, which were prepared by a facing target sputtering method followed by a subsequent annealing process to purposely study the N inter-diffusive effect. It is observed that by tuning the Fe layer thickness from 2 nm to 5 nm, the magnetic properties of the resulting product varies substantially. According to X-ray diffraction, an additional peak, indexed to Fe16N2 (004), was developed in the sample with thinner (2 nm) underlayer. Its corresponding PNR study shows a 4πMs of up to 2.82 T towards the substrate interface, which is 14% higher than the known limit (Fe65Co35 ∼ 4πMs = 2.45 T). We attribute this giant magnetization to the presence of chemically ordered Fe1N2. We have seen evidence that the high Ms is favorably stabilized due to the lattice misfit. The thickness range is consistent with the strained region of the films. This depth-dependent saturation magnetization analysis can shed a light to help understand the previous magnetization reports by classical magnetometry methods for the samples prepared using the same underlayer.

AB - We used polarized neutron reflectometry (PNR) to investigate the depth-dependent saturation magnetization (4πMs) of bi-layer structured Fe-N/Fe grown on MgO substrates, which were prepared by a facing target sputtering method followed by a subsequent annealing process to purposely study the N inter-diffusive effect. It is observed that by tuning the Fe layer thickness from 2 nm to 5 nm, the magnetic properties of the resulting product varies substantially. According to X-ray diffraction, an additional peak, indexed to Fe16N2 (004), was developed in the sample with thinner (2 nm) underlayer. Its corresponding PNR study shows a 4πMs of up to 2.82 T towards the substrate interface, which is 14% higher than the known limit (Fe65Co35 ∼ 4πMs = 2.45 T). We attribute this giant magnetization to the presence of chemically ordered Fe1N2. We have seen evidence that the high Ms is favorably stabilized due to the lattice misfit. The thickness range is consistent with the strained region of the films. This depth-dependent saturation magnetization analysis can shed a light to help understand the previous magnetization reports by classical magnetometry methods for the samples prepared using the same underlayer.

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KW - iron nitride

KW - polarized neutron reflectometry

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GROWTH and DEPTH-DEPENDENCE of SATURATION MAGNETIZATION of IRON NITRIDE THIN FILMS on MgO SUBSTRATE

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