Effect of shell thickness on the exchange bias blocking temperature and coercivity in Co-CoO core-shell nanoparticles

S. Thomas, K. Reethu, T. Thanveer, M. T.Z. Myint, S. H. Al-Harthi

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The exchange bias blocking temperature distribution of naturally oxidized Co-CoO core-shell nanoparticles exhibits two distinct signatures. These are associated with the existence of two magnetic entities which are responsible for the temperature dependence of an exchange bias field. One is from the CoO grains which undergo thermally activated magnetization reversal. The other is from the disordered spins at the Co-CoO interface which exhibits spin-glass-like behavior. We investigated the oxide shell thickness dependence of the exchange bias effect. For particles with a 3 nm thick CoO shell, the predominant contribution to the temperature dependence of exchange bias is the interfacial spin-glass layer. On increasing the shell thickness to 4 nm, the contribution from the spin-glass layer decreases, while upholding the antiferromagnetic grain contribution. For samples with a 4 nm CoO shell, the exchange bias training was minimal. On the other hand, 3 nm samples exhibited both the training effect and a peak in coercivity at an intermediate set temperature Ta. This is explained using a magnetic core-shell model including disordered spins at the interface.

Original languageEnglish
Article number063902
JournalJournal of Applied Physics
Volume122
Issue number6
DOIs
Publication statusPublished - Aug 14 2017

Fingerprint

coercivity
nanoparticles
spin glass
education
temperature
magnetic cores
temperature dependence
temperature distribution
signatures
magnetization
oxides

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Effect of shell thickness on the exchange bias blocking temperature and coercivity in Co-CoO core-shell nanoparticles. / Thomas, S.; Reethu, K.; Thanveer, T.; Myint, M. T.Z.; Al-Harthi, S. H.

In: Journal of Applied Physics, Vol. 122, No. 6, 063902, 14.08.2017.

Research output: Contribution to journalArticle

@article{d8a2027998104e9a8a76b49dd67722cc,
title = "Effect of shell thickness on the exchange bias blocking temperature and coercivity in Co-CoO core-shell nanoparticles",
abstract = "The exchange bias blocking temperature distribution of naturally oxidized Co-CoO core-shell nanoparticles exhibits two distinct signatures. These are associated with the existence of two magnetic entities which are responsible for the temperature dependence of an exchange bias field. One is from the CoO grains which undergo thermally activated magnetization reversal. The other is from the disordered spins at the Co-CoO interface which exhibits spin-glass-like behavior. We investigated the oxide shell thickness dependence of the exchange bias effect. For particles with a 3 nm thick CoO shell, the predominant contribution to the temperature dependence of exchange bias is the interfacial spin-glass layer. On increasing the shell thickness to 4 nm, the contribution from the spin-glass layer decreases, while upholding the antiferromagnetic grain contribution. For samples with a 4 nm CoO shell, the exchange bias training was minimal. On the other hand, 3 nm samples exhibited both the training effect and a peak in coercivity at an intermediate set temperature Ta. This is explained using a magnetic core-shell model including disordered spins at the interface.",
author = "S. Thomas and K. Reethu and T. Thanveer and Myint, {M. T.Z.} and Al-Harthi, {S. H.}",
year = "2017",
month = "8",
day = "14",
doi = "10.1063/1.4997883",
language = "English",
volume = "122",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "6",

}

TY - JOUR

T1 - Effect of shell thickness on the exchange bias blocking temperature and coercivity in Co-CoO core-shell nanoparticles

AU - Thomas, S.

AU - Reethu, K.

AU - Thanveer, T.

AU - Myint, M. T.Z.

AU - Al-Harthi, S. H.

PY - 2017/8/14

Y1 - 2017/8/14

N2 - The exchange bias blocking temperature distribution of naturally oxidized Co-CoO core-shell nanoparticles exhibits two distinct signatures. These are associated with the existence of two magnetic entities which are responsible for the temperature dependence of an exchange bias field. One is from the CoO grains which undergo thermally activated magnetization reversal. The other is from the disordered spins at the Co-CoO interface which exhibits spin-glass-like behavior. We investigated the oxide shell thickness dependence of the exchange bias effect. For particles with a 3 nm thick CoO shell, the predominant contribution to the temperature dependence of exchange bias is the interfacial spin-glass layer. On increasing the shell thickness to 4 nm, the contribution from the spin-glass layer decreases, while upholding the antiferromagnetic grain contribution. For samples with a 4 nm CoO shell, the exchange bias training was minimal. On the other hand, 3 nm samples exhibited both the training effect and a peak in coercivity at an intermediate set temperature Ta. This is explained using a magnetic core-shell model including disordered spins at the interface.

AB - The exchange bias blocking temperature distribution of naturally oxidized Co-CoO core-shell nanoparticles exhibits two distinct signatures. These are associated with the existence of two magnetic entities which are responsible for the temperature dependence of an exchange bias field. One is from the CoO grains which undergo thermally activated magnetization reversal. The other is from the disordered spins at the Co-CoO interface which exhibits spin-glass-like behavior. We investigated the oxide shell thickness dependence of the exchange bias effect. For particles with a 3 nm thick CoO shell, the predominant contribution to the temperature dependence of exchange bias is the interfacial spin-glass layer. On increasing the shell thickness to 4 nm, the contribution from the spin-glass layer decreases, while upholding the antiferromagnetic grain contribution. For samples with a 4 nm CoO shell, the exchange bias training was minimal. On the other hand, 3 nm samples exhibited both the training effect and a peak in coercivity at an intermediate set temperature Ta. This is explained using a magnetic core-shell model including disordered spins at the interface.

UR - http://www.scopus.com/inward/record.url?scp=85027257542&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85027257542&partnerID=8YFLogxK

U2 - 10.1063/1.4997883

DO - 10.1063/1.4997883

M3 - Article

AN - SCOPUS:85027257542

VL - 122

JO - Journal of Applied Physics

JF - Journal of Applied Physics

SN - 0021-8979

IS - 6

M1 - 063902

ER -