Tunneling anisotropic magnetoresistance in C60-based organic spintronic systems

Research output: Contribution to journalArticleAcademicpeer-review

17 Citations (Scopus)

Abstract

C 60 fullerenes are interesting molecular semiconductors for spintronics since they exhibit weak spin-orbit and hyperfine interactions, which is a prerequisite for long spin lifetimes. We report spin-polarized transport in spin-valve-like structures containing ultrathin (<10 nm) C 60 layers, ferromagnetic (FM) epitaxial face-centered-cubic (fcc) Co (111) contacts, AlO x tunnel barriers, and nonmagnetic Al counter electrodes. Even though genuine spin-valve behavior cannot occur for only one FM contact, we find significant tunneling anisotropic magnetoresistance (TAMR) upon rotating the in-plane magnetization, originating from spin-orbit interaction (SOI) induced anisotropy of the fcc (111) Co bands. The uniaxial magnetocrystalline anisotropy of the Co electrodes results in a predominantly twofold symmetric in-plane TAMR effect. We investigated the TAMR effect in the direct tunneling regime (2 nm C 60 ), at the transition point to two-step tunneling (4 nm C 60 ), and in the multistep regime (8 nm C 60 ). A sizable TAMR of 4.5% is found at 5 K under application of a 500-mT in-plane magnetic field for C 60 layers of 2 nm, which is strongly suppressed at 8 nm thickness, indicating that TAMR may strongly contribute to the “spin-valve‿ signal for direct tunneling, but not for multistep tunneling. The TAMR effect is proposed to be due to a combination of SOI induced modulation of the tunneling DOS upon rotating the in-plane magnetization of the fcc epitaxial Co thin film, resonant tunneling processes involving interfacial states, and different Bychkov-Rashba SOI at the different interfaces.
Original languageUndefined
Pages (from-to)174419
Number of pages8
JournalPhysical review B: Condensed matter and materials physics
Volume89
Issue number17
DOIs
Publication statusPublished - 16 May 2014

Keywords

  • EWI-25380
  • IR-92934
  • METIS-309699

Cite this

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title = "Tunneling anisotropic magnetoresistance in C60-based organic spintronic systems",
abstract = "C 60 fullerenes are interesting molecular semiconductors for spintronics since they exhibit weak spin-orbit and hyperfine interactions, which is a prerequisite for long spin lifetimes. We report spin-polarized transport in spin-valve-like structures containing ultrathin (<10 nm) C 60 layers, ferromagnetic (FM) epitaxial face-centered-cubic (fcc) Co (111) contacts, AlO x tunnel barriers, and nonmagnetic Al counter electrodes. Even though genuine spin-valve behavior cannot occur for only one FM contact, we find significant tunneling anisotropic magnetoresistance (TAMR) upon rotating the in-plane magnetization, originating from spin-orbit interaction (SOI) induced anisotropy of the fcc (111) Co bands. The uniaxial magnetocrystalline anisotropy of the Co electrodes results in a predominantly twofold symmetric in-plane TAMR effect. We investigated the TAMR effect in the direct tunneling regime (2 nm C 60 ), at the transition point to two-step tunneling (4 nm C 60 ), and in the multistep regime (8 nm C 60 ). A sizable TAMR of 4.5{\%} is found at 5 K under application of a 500-mT in-plane magnetic field for C 60 layers of 2 nm, which is strongly suppressed at 8 nm thickness, indicating that TAMR may strongly contribute to the “spin-valve‿ signal for direct tunneling, but not for multistep tunneling. The TAMR effect is proposed to be due to a combination of SOI induced modulation of the tunneling DOS upon rotating the in-plane magnetization of the fcc epitaxial Co thin film, resonant tunneling processes involving interfacial states, and different Bychkov-Rashba SOI at the different interfaces.",
keywords = "EWI-25380, IR-92934, METIS-309699",
author = "Kai Wang and Sanderink, {Johannes G.M.} and Thijs Bolhuis and {van der Wiel}, {Wilfred Gerard} and {de Jong}, {Machiel Pieter}",
note = "eemcs-eprint-25380",
year = "2014",
month = "5",
day = "16",
doi = "10.1103/PhysRevB.89.174419",
language = "Undefined",
volume = "89",
pages = "174419",
journal = "Physical review B: Condensed matter and materials physics",
issn = "1098-0121",
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Tunneling anisotropic magnetoresistance in C60-based organic spintronic systems. / Wang, Kai; 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. 89, No. 17, 16.05.2014, p. 174419.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Tunneling anisotropic magnetoresistance in C60-based organic spintronic systems

AU - Wang, Kai

AU - Sanderink, Johannes G.M.

AU - Bolhuis, Thijs

AU - van der Wiel, Wilfred Gerard

AU - de Jong, Machiel Pieter

N1 - eemcs-eprint-25380

PY - 2014/5/16

Y1 - 2014/5/16

N2 - C 60 fullerenes are interesting molecular semiconductors for spintronics since they exhibit weak spin-orbit and hyperfine interactions, which is a prerequisite for long spin lifetimes. We report spin-polarized transport in spin-valve-like structures containing ultrathin (<10 nm) C 60 layers, ferromagnetic (FM) epitaxial face-centered-cubic (fcc) Co (111) contacts, AlO x tunnel barriers, and nonmagnetic Al counter electrodes. Even though genuine spin-valve behavior cannot occur for only one FM contact, we find significant tunneling anisotropic magnetoresistance (TAMR) upon rotating the in-plane magnetization, originating from spin-orbit interaction (SOI) induced anisotropy of the fcc (111) Co bands. The uniaxial magnetocrystalline anisotropy of the Co electrodes results in a predominantly twofold symmetric in-plane TAMR effect. We investigated the TAMR effect in the direct tunneling regime (2 nm C 60 ), at the transition point to two-step tunneling (4 nm C 60 ), and in the multistep regime (8 nm C 60 ). A sizable TAMR of 4.5% is found at 5 K under application of a 500-mT in-plane magnetic field for C 60 layers of 2 nm, which is strongly suppressed at 8 nm thickness, indicating that TAMR may strongly contribute to the “spin-valve‿ signal for direct tunneling, but not for multistep tunneling. The TAMR effect is proposed to be due to a combination of SOI induced modulation of the tunneling DOS upon rotating the in-plane magnetization of the fcc epitaxial Co thin film, resonant tunneling processes involving interfacial states, and different Bychkov-Rashba SOI at the different interfaces.

AB - C 60 fullerenes are interesting molecular semiconductors for spintronics since they exhibit weak spin-orbit and hyperfine interactions, which is a prerequisite for long spin lifetimes. We report spin-polarized transport in spin-valve-like structures containing ultrathin (<10 nm) C 60 layers, ferromagnetic (FM) epitaxial face-centered-cubic (fcc) Co (111) contacts, AlO x tunnel barriers, and nonmagnetic Al counter electrodes. Even though genuine spin-valve behavior cannot occur for only one FM contact, we find significant tunneling anisotropic magnetoresistance (TAMR) upon rotating the in-plane magnetization, originating from spin-orbit interaction (SOI) induced anisotropy of the fcc (111) Co bands. The uniaxial magnetocrystalline anisotropy of the Co electrodes results in a predominantly twofold symmetric in-plane TAMR effect. We investigated the TAMR effect in the direct tunneling regime (2 nm C 60 ), at the transition point to two-step tunneling (4 nm C 60 ), and in the multistep regime (8 nm C 60 ). A sizable TAMR of 4.5% is found at 5 K under application of a 500-mT in-plane magnetic field for C 60 layers of 2 nm, which is strongly suppressed at 8 nm thickness, indicating that TAMR may strongly contribute to the “spin-valve‿ signal for direct tunneling, but not for multistep tunneling. The TAMR effect is proposed to be due to a combination of SOI induced modulation of the tunneling DOS upon rotating the in-plane magnetization of the fcc epitaxial Co thin film, resonant tunneling processes involving interfacial states, and different Bychkov-Rashba SOI at the different interfaces.

KW - EWI-25380

KW - IR-92934

KW - METIS-309699

U2 - 10.1103/PhysRevB.89.174419

DO - 10.1103/PhysRevB.89.174419

M3 - Article

VL - 89

SP - 174419

JO - Physical review B: Condensed matter and materials physics

JF - Physical review B: Condensed matter and materials physics

SN - 1098-0121

IS - 17

ER -