Photoinduced Superparamagnetism in Nanostructured a-Fe203

I. Ross Macdonald; Russell F. Howe; Sina Saremi-Yarahmadi; K. G. U. Wijayantha

doi:10.1021/jz100650w

Photoinduced Superparamagnetism in Nanostructured a-Fe203

I. Ross Macdonald, Russell F. Howe, Sina Saremi-Yarahmadi, K. G. U. Wijayantha

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

23 Citations (Scopus)

Abstract

This Letter reports a remarkable influence of light on the magnetic properties of nanocrystalline a-Fe203. EPR spectroscopy shows that the a-Fe203 is superparamagnetic, showing an intense narrow EPR signal at room temperature which shifts to a lower field and broadens to be barely detectable at 77 K Or below In situ irradiation of samples held in vacuo at 4 or 77 K with near-UVor visible light causes the appearance of an intense new EPR signal, which decays immediately after the irradiation is stopped. We suggest that the generation of conduction band electrons by irradiation Into the band gap of the a-Fe203 moderates the coupling between the magnetic domains in these nanocrystals This effect is largely suppressed in the presence of adsorbed oxygen, which can scavenge conduction band electrons.

Original language	English
Pages (from-to)	2488-2492
Number of pages	5
Journal	The Journal of Physical Chemistry Letters
Volume	1
Issue number	16
DOIs	https://doi.org/10.1021/jz100650w
Publication status	Published - 19 Aug 2010

Keywords

Alpha-FE2O3 films
Nanoparticles
Water
Oxide
Resonance
Electrodes
Particles
Oxidation
Hematite
Anatase

Access to Document

10.1021/jz100650w

Cite this

@article{208704354ef04cf29c2abfeacc93ed85,

title = "Photoinduced Superparamagnetism in Nanostructured a-Fe203",

abstract = "This Letter reports a remarkable influence of light on the magnetic properties of nanocrystalline a-Fe203. EPR spectroscopy shows that the a-Fe203 is superparamagnetic, showing an intense narrow EPR signal at room temperature which shifts to a lower field and broadens to be barely detectable at 77 K Or below In situ irradiation of samples held in vacuo at 4 or 77 K with near-UVor visible light causes the appearance of an intense new EPR signal, which decays immediately after the irradiation is stopped. We suggest that the generation of conduction band electrons by irradiation Into the band gap of the a-Fe203 moderates the coupling between the magnetic domains in these nanocrystals This effect is largely suppressed in the presence of adsorbed oxygen, which can scavenge conduction band electrons.",

keywords = "Alpha-FE2O3 films, Nanoparticles, Water, Oxide, Resonance, Electrodes, Particles, Oxidation, Hematite, Anatase",

author = "Macdonald, {I. Ross} and Howe, {Russell F.} and Sina Saremi-Yarahmadi and Wijayantha, {K. G. U.}",

year = "2010",

month = aug,

day = "19",

doi = "10.1021/jz100650w",

language = "English",

volume = "1",

pages = "2488--2492",

journal = "The Journal of Physical Chemistry Letters",

issn = "1948-7185",

publisher = "American Chemical Society",

number = "16",

}

TY - JOUR

T1 - Photoinduced Superparamagnetism in Nanostructured a-Fe203

AU - Macdonald, I. Ross

AU - Howe, Russell F.

AU - Saremi-Yarahmadi, Sina

AU - Wijayantha, K. G. U.

PY - 2010/8/19

Y1 - 2010/8/19

N2 - This Letter reports a remarkable influence of light on the magnetic properties of nanocrystalline a-Fe203. EPR spectroscopy shows that the a-Fe203 is superparamagnetic, showing an intense narrow EPR signal at room temperature which shifts to a lower field and broadens to be barely detectable at 77 K Or below In situ irradiation of samples held in vacuo at 4 or 77 K with near-UVor visible light causes the appearance of an intense new EPR signal, which decays immediately after the irradiation is stopped. We suggest that the generation of conduction band electrons by irradiation Into the band gap of the a-Fe203 moderates the coupling between the magnetic domains in these nanocrystals This effect is largely suppressed in the presence of adsorbed oxygen, which can scavenge conduction band electrons.

AB - This Letter reports a remarkable influence of light on the magnetic properties of nanocrystalline a-Fe203. EPR spectroscopy shows that the a-Fe203 is superparamagnetic, showing an intense narrow EPR signal at room temperature which shifts to a lower field and broadens to be barely detectable at 77 K Or below In situ irradiation of samples held in vacuo at 4 or 77 K with near-UVor visible light causes the appearance of an intense new EPR signal, which decays immediately after the irradiation is stopped. We suggest that the generation of conduction band electrons by irradiation Into the band gap of the a-Fe203 moderates the coupling between the magnetic domains in these nanocrystals This effect is largely suppressed in the presence of adsorbed oxygen, which can scavenge conduction band electrons.

KW - Alpha-FE2O3 films

KW - Nanoparticles

KW - Water

KW - Oxide

KW - Resonance

KW - Electrodes

KW - Particles

KW - Oxidation

KW - Hematite

KW - Anatase

U2 - 10.1021/jz100650w

DO - 10.1021/jz100650w

M3 - Article

SN - 1948-7185

VL - 1

SP - 2488

EP - 2492

JO - The Journal of Physical Chemistry Letters

JF - The Journal of Physical Chemistry Letters

IS - 16

ER -

Photoinduced Superparamagnetism in Nanostructured a-Fe203

Abstract

Keywords

Access to Document

Fingerprint

Cite this