Tunneling anisotropic magnetoresistance in Co/AIOx/Al tunnel junctions with fcc Co (111) electrodes

Kai Wang, T. Lan Ahn Tran, Peter Brinks, P. Brinks, Johannes G.M. Sanderink, Thijs Bolhuis, Wilfred Gerard van der Wiel, Machiel Pieter de Jong

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Abstract

Tunneling anisotropic magnetoresistance (TAMR) has been characterized in junctions comprised of face-centered cubic (fcc) Co (111) ferromagnetic electrodes grown epitaxially on sapphire substrates, amorphous AlOx tunnel barriers, and nonmagnetic Al counterelectrodes. Large TAMR ratios have been found, up to similar to 7.5% and similar to 11% (at 5 K), for the in-plane and out-of-plane magnetization geometry, respectively. Such large TAMR values were not expected a priori, given the weak anisotropy of the (bulk) Co bands due to spin-orbit interaction, and the absence of Co (111) surface states that cross the Fermi energy. Both the in-plane and out-of-plane TAMR effects exhibit a predominantly twofold symmetry, and a strong bias dependence. The in-plane TAMR shows a maximum along the (twofold) magnetic hard axis, suggesting a relation between magnetic anisotropy and TAMR. We propose that uniaxial strain in combination with Bychkov-Rashba spin-orbit interaction, producing an interfacial tunneling DOS that depends on the magnetization direction, is responsible for the TAMR effect. The importance of the interfacial Co/AlOx (electronic) structure for the TAMR effect is underlined by measurements on junctions with overoxidized AlOx barriers, which show markedly different bias and angle dependence.
Original languageUndefined
Article number05477
Pages (from-to)054407
Number of pages8
JournalPhysical review B: Condensed matter and materials physics
Volume88
Issue number5
DOIs
Publication statusPublished - 9 Aug 2013

Keywords

  • EWI-24393
  • IR-89179
  • METIS-299871

Cite this

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title = "Tunneling anisotropic magnetoresistance in Co/AIOx/Al tunnel junctions with fcc Co (111) electrodes",
abstract = "Tunneling anisotropic magnetoresistance (TAMR) has been characterized in junctions comprised of face-centered cubic (fcc) Co (111) ferromagnetic electrodes grown epitaxially on sapphire substrates, amorphous AlOx tunnel barriers, and nonmagnetic Al counterelectrodes. Large TAMR ratios have been found, up to similar to 7.5{\%} and similar to 11{\%} (at 5 K), for the in-plane and out-of-plane magnetization geometry, respectively. Such large TAMR values were not expected a priori, given the weak anisotropy of the (bulk) Co bands due to spin-orbit interaction, and the absence of Co (111) surface states that cross the Fermi energy. Both the in-plane and out-of-plane TAMR effects exhibit a predominantly twofold symmetry, and a strong bias dependence. The in-plane TAMR shows a maximum along the (twofold) magnetic hard axis, suggesting a relation between magnetic anisotropy and TAMR. We propose that uniaxial strain in combination with Bychkov-Rashba spin-orbit interaction, producing an interfacial tunneling DOS that depends on the magnetization direction, is responsible for the TAMR effect. The importance of the interfacial Co/AlOx (electronic) structure for the TAMR effect is underlined by measurements on junctions with overoxidized AlOx barriers, which show markedly different bias and angle dependence.",
keywords = "EWI-24393, IR-89179, METIS-299871",
author = "Kai Wang and Tran, {T. Lan Ahn} and Peter Brinks and P. Brinks and Sanderink, {Johannes G.M.} and Thijs Bolhuis and {van der Wiel}, {Wilfred Gerard} and {de Jong}, {Machiel Pieter}",
year = "2013",
month = "8",
day = "9",
doi = "10.1103/PhysRevB.88.054407",
language = "Undefined",
volume = "88",
pages = "054407",
journal = "Physical review B: Condensed matter and materials physics",
issn = "1098-0121",
publisher = "American Physical Society",
number = "5",

}

Tunneling anisotropic magnetoresistance in Co/AIOx/Al tunnel junctions with fcc Co (111) electrodes. / Wang, Kai; Tran, T. Lan Ahn; Brinks, Peter; Brinks, P.; Sanderink, Johannes G.M.; Bolhuis, Thijs; van der Wiel, Wilfred Gerard; de Jong, Machiel Pieter.

In: Physical review B: Condensed matter and materials physics, Vol. 88, No. 5, 05477, 09.08.2013, p. 054407.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Tunneling anisotropic magnetoresistance in Co/AIOx/Al tunnel junctions with fcc Co (111) electrodes

AU - Wang, Kai

AU - Tran, T. Lan Ahn

AU - Brinks, Peter

AU - Brinks, P.

AU - Sanderink, Johannes G.M.

AU - Bolhuis, Thijs

AU - van der Wiel, Wilfred Gerard

AU - de Jong, Machiel Pieter

PY - 2013/8/9

Y1 - 2013/8/9

N2 - Tunneling anisotropic magnetoresistance (TAMR) has been characterized in junctions comprised of face-centered cubic (fcc) Co (111) ferromagnetic electrodes grown epitaxially on sapphire substrates, amorphous AlOx tunnel barriers, and nonmagnetic Al counterelectrodes. Large TAMR ratios have been found, up to similar to 7.5% and similar to 11% (at 5 K), for the in-plane and out-of-plane magnetization geometry, respectively. Such large TAMR values were not expected a priori, given the weak anisotropy of the (bulk) Co bands due to spin-orbit interaction, and the absence of Co (111) surface states that cross the Fermi energy. Both the in-plane and out-of-plane TAMR effects exhibit a predominantly twofold symmetry, and a strong bias dependence. The in-plane TAMR shows a maximum along the (twofold) magnetic hard axis, suggesting a relation between magnetic anisotropy and TAMR. We propose that uniaxial strain in combination with Bychkov-Rashba spin-orbit interaction, producing an interfacial tunneling DOS that depends on the magnetization direction, is responsible for the TAMR effect. The importance of the interfacial Co/AlOx (electronic) structure for the TAMR effect is underlined by measurements on junctions with overoxidized AlOx barriers, which show markedly different bias and angle dependence.

AB - Tunneling anisotropic magnetoresistance (TAMR) has been characterized in junctions comprised of face-centered cubic (fcc) Co (111) ferromagnetic electrodes grown epitaxially on sapphire substrates, amorphous AlOx tunnel barriers, and nonmagnetic Al counterelectrodes. Large TAMR ratios have been found, up to similar to 7.5% and similar to 11% (at 5 K), for the in-plane and out-of-plane magnetization geometry, respectively. Such large TAMR values were not expected a priori, given the weak anisotropy of the (bulk) Co bands due to spin-orbit interaction, and the absence of Co (111) surface states that cross the Fermi energy. Both the in-plane and out-of-plane TAMR effects exhibit a predominantly twofold symmetry, and a strong bias dependence. The in-plane TAMR shows a maximum along the (twofold) magnetic hard axis, suggesting a relation between magnetic anisotropy and TAMR. We propose that uniaxial strain in combination with Bychkov-Rashba spin-orbit interaction, producing an interfacial tunneling DOS that depends on the magnetization direction, is responsible for the TAMR effect. The importance of the interfacial Co/AlOx (electronic) structure for the TAMR effect is underlined by measurements on junctions with overoxidized AlOx barriers, which show markedly different bias and angle dependence.

KW - EWI-24393

KW - IR-89179

KW - METIS-299871

U2 - 10.1103/PhysRevB.88.054407

DO - 10.1103/PhysRevB.88.054407

M3 - Article

VL - 88

SP - 054407

JO - Physical review B: Condensed matter and materials physics

JF - Physical review B: Condensed matter and materials physics

SN - 1098-0121

IS - 5

M1 - 05477

ER -