Crystalline CoFeB/graphite interfaces for carbon spintronics fabricated by solid phase epitaxy

P.K.J. Wong, Elmer van Geijn, E. van Geijn, W. Zhang, A.A. Starikov, T. Lan Ahn Tran, Johannes G.M. Sanderink, Martin Herman Siekman, Gerardus H.L.A. Brocks, Paul J. Kelly, Wilfred Gerard van der Wiel, Machiel Pieter de Jong

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Abstract

Structurally ordered interfaces between ferromagnetic electrodes and graphene or graphite are of great interest for carbon spintronics, since they allow spin-filtering due to k-vector conservation. By solid phase epitaxy of amorphous/nanocrystalline CoFeB at elevated temperatures, the feasibility of fabricating crystalline interfaces between a 3d ferromagnetic alloy and graphite is demonstrated, without suffering from the unwetting problem that was commonly seen in many previous studies with 3d transition metals. The films fabricated on graphite in this way are found to have a strong body-centered-cubic (110) texture, albeit without a unique, well-defined in-plane epitaxial relationship with the substrate lattice. Using various X-ray spectroscopic techniques, it is shown that boron suppresses the formation of CoFe-O during CoFeB deposition, and then diffuses out of the CoFe lattice. Segregation of B occurred exclusively to the film surface upon in situ annealing, and not to the interface between CoFeB and graphite. This is favorable for obtaining a high spin polarization at the hybrid CoFe/graphite crystalline interface. The Co and Fe spin moments in the crystalline film, determined by X-ray magnetic circular dichroism, are found to be bulk-like, while their orbital moments show an unusual giant enhancement which has yet to be understood.
Original languageUndefined
Pages (from-to)4933-4940
Number of pages8
JournalAdvanced functional materials
Volume23
Issue number39
DOIs
Publication statusPublished - 15 Apr 2013

Keywords

  • solid phase epitaxy
  • EWI-24391
  • Amorphous ferromagnetic alloys
  • IR-89177
  • Spintronics
  • graphite
  • METIS-298196
  • Interfaces

Cite this

@article{6faf7c1f1e80412d8373830b9c15f66c,
title = "Crystalline CoFeB/graphite interfaces for carbon spintronics fabricated by solid phase epitaxy",
abstract = "Structurally ordered interfaces between ferromagnetic electrodes and graphene or graphite are of great interest for carbon spintronics, since they allow spin-filtering due to k-vector conservation. By solid phase epitaxy of amorphous/nanocrystalline CoFeB at elevated temperatures, the feasibility of fabricating crystalline interfaces between a 3d ferromagnetic alloy and graphite is demonstrated, without suffering from the unwetting problem that was commonly seen in many previous studies with 3d transition metals. The films fabricated on graphite in this way are found to have a strong body-centered-cubic (110) texture, albeit without a unique, well-defined in-plane epitaxial relationship with the substrate lattice. Using various X-ray spectroscopic techniques, it is shown that boron suppresses the formation of CoFe-O during CoFeB deposition, and then diffuses out of the CoFe lattice. Segregation of B occurred exclusively to the film surface upon in situ annealing, and not to the interface between CoFeB and graphite. This is favorable for obtaining a high spin polarization at the hybrid CoFe/graphite crystalline interface. The Co and Fe spin moments in the crystalline film, determined by X-ray magnetic circular dichroism, are found to be bulk-like, while their orbital moments show an unusual giant enhancement which has yet to be understood.",
keywords = "solid phase epitaxy, EWI-24391, Amorphous ferromagnetic alloys, IR-89177, Spintronics, graphite, METIS-298196, Interfaces",
author = "P.K.J. Wong and {van Geijn}, Elmer and {van Geijn}, E. and W. Zhang and A.A. Starikov and Tran, {T. Lan Ahn} and Sanderink, {Johannes G.M.} and Siekman, {Martin Herman} and Brocks, {Gerardus H.L.A.} and Kelly, {Paul J.} and {van der Wiel}, {Wilfred Gerard} and {de Jong}, {Machiel Pieter}",
year = "2013",
month = "4",
day = "15",
doi = "10.1002/adfm.201203460",
language = "Undefined",
volume = "23",
pages = "4933--4940",
journal = "Advanced functional materials",
issn = "1616-301X",
publisher = "Wiley-VCH Verlag",
number = "39",

}

Crystalline CoFeB/graphite interfaces for carbon spintronics fabricated by solid phase epitaxy. / Wong, P.K.J.; van Geijn, Elmer; van Geijn, E.; Zhang, W.; Starikov, A.A.; Tran, T. Lan Ahn; Sanderink, Johannes G.M.; Siekman, Martin Herman; Brocks, Gerardus H.L.A.; Kelly, Paul J.; van der Wiel, Wilfred Gerard; de Jong, Machiel Pieter.

In: Advanced functional materials, Vol. 23, No. 39, 15.04.2013, p. 4933-4940.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Crystalline CoFeB/graphite interfaces for carbon spintronics fabricated by solid phase epitaxy

AU - Wong, P.K.J.

AU - van Geijn, Elmer

AU - van Geijn, E.

AU - Zhang, W.

AU - Starikov, A.A.

AU - Tran, T. Lan Ahn

AU - Sanderink, Johannes G.M.

AU - Siekman, Martin Herman

AU - Brocks, Gerardus H.L.A.

AU - Kelly, Paul J.

AU - van der Wiel, Wilfred Gerard

AU - de Jong, Machiel Pieter

PY - 2013/4/15

Y1 - 2013/4/15

N2 - Structurally ordered interfaces between ferromagnetic electrodes and graphene or graphite are of great interest for carbon spintronics, since they allow spin-filtering due to k-vector conservation. By solid phase epitaxy of amorphous/nanocrystalline CoFeB at elevated temperatures, the feasibility of fabricating crystalline interfaces between a 3d ferromagnetic alloy and graphite is demonstrated, without suffering from the unwetting problem that was commonly seen in many previous studies with 3d transition metals. The films fabricated on graphite in this way are found to have a strong body-centered-cubic (110) texture, albeit without a unique, well-defined in-plane epitaxial relationship with the substrate lattice. Using various X-ray spectroscopic techniques, it is shown that boron suppresses the formation of CoFe-O during CoFeB deposition, and then diffuses out of the CoFe lattice. Segregation of B occurred exclusively to the film surface upon in situ annealing, and not to the interface between CoFeB and graphite. This is favorable for obtaining a high spin polarization at the hybrid CoFe/graphite crystalline interface. The Co and Fe spin moments in the crystalline film, determined by X-ray magnetic circular dichroism, are found to be bulk-like, while their orbital moments show an unusual giant enhancement which has yet to be understood.

AB - Structurally ordered interfaces between ferromagnetic electrodes and graphene or graphite are of great interest for carbon spintronics, since they allow spin-filtering due to k-vector conservation. By solid phase epitaxy of amorphous/nanocrystalline CoFeB at elevated temperatures, the feasibility of fabricating crystalline interfaces between a 3d ferromagnetic alloy and graphite is demonstrated, without suffering from the unwetting problem that was commonly seen in many previous studies with 3d transition metals. The films fabricated on graphite in this way are found to have a strong body-centered-cubic (110) texture, albeit without a unique, well-defined in-plane epitaxial relationship with the substrate lattice. Using various X-ray spectroscopic techniques, it is shown that boron suppresses the formation of CoFe-O during CoFeB deposition, and then diffuses out of the CoFe lattice. Segregation of B occurred exclusively to the film surface upon in situ annealing, and not to the interface between CoFeB and graphite. This is favorable for obtaining a high spin polarization at the hybrid CoFe/graphite crystalline interface. The Co and Fe spin moments in the crystalline film, determined by X-ray magnetic circular dichroism, are found to be bulk-like, while their orbital moments show an unusual giant enhancement which has yet to be understood.

KW - solid phase epitaxy

KW - EWI-24391

KW - Amorphous ferromagnetic alloys

KW - IR-89177

KW - Spintronics

KW - graphite

KW - METIS-298196

KW - Interfaces

U2 - 10.1002/adfm.201203460

DO - 10.1002/adfm.201203460

M3 - Article

VL - 23

SP - 4933

EP - 4940

JO - Advanced functional materials

JF - Advanced functional materials

SN - 1616-301X

IS - 39

ER -

Wong PKJ, van Geijn E, van Geijn E, Zhang W, Starikov AA, Tran TLA et al. Crystalline CoFeB/graphite interfaces for carbon spintronics fabricated by solid phase epitaxy. Advanced functional materials. 2013 Apr 15;23(39):4933-4940. https://doi.org/10.1002/adfm.201203460