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Light-induced magnetism in polycrystalline and thin films of Cr2O3

Sho Sasaki 1Yufeng Zhang 1Osami Yanagisawa 2Mitsuru Izumi 1

1. Tokyo Univ of Marine Science and Technology (TUMSAT), 2-1-6, Etchu-jima, Koto-ku, Tokyo 1358533, Japan
2. Yuge Natinal College of Maritime Technology (YMCNT), Ehime 7942593, Japan

Abstract

We studied on a chromium oxide Cr2O3 to investigate near-infrared (NIR) light-induced magnetism function at room temperature. It is well known that the Cr2O3 has a corundum crystal structure with antiferromagnetic (AF) transition at TN ~ 308 K. A X-band electron-spin resonance (ESR) spectrometer and a SQUID magnetometer were employed to clarify magnetic behavior in the Cr2O3 under the illumination of NIR light (λ = 1064 nm). Under the light illumination, the light-induced ESR signal appears above 250 K and is remarkably enhanced around room temperature. Contrary, with visible green light (λ = 532 nm), the ESR profile does not show any change. The light-induced effect is strongly dependent on the irradiation light wavelength. We conclude the light-induced ESR below TN may come from light-excited carriers associating with a reentrance from antiferromagnetic to paramagnetic spin order. Thin films were successfully prepared by a RF magnetron sputtering and a sol-gel method. The TN of the thin film was increased from 308 K to about 400 K. We discuss intriguing properties on light-induced effect for both polycrystalline and thin films and state the chromate is a candidature to be applied to NIR detection industrial devices.

Keywords: light-induced magnetism, Perovskite structure, Spin State transition, ESR

 

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Related papers

Presentation: Oral at E-MRS Fall Meeting 2006, Symposium K, by Sho Sasaki
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-06-05 09:50
Revised:   2009-06-07 00:44