ORCID Profile
0000-0002-9691-0636
Current Organisation
University of California, San Diego
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Publisher: American Chemical Society (ACS)
Date: 24-08-2020
Publisher: The Royal Society
Date: 28-10-2012
Abstract: We report room-temperature ferromagnetism (FM) in highly conducting, transparent anatase Ti 1− x Ta x O 2 ( x ∼0.05) thin films grown by pulsed laser deposition on LaAlO 3 substrates. Rutherford backscattering spectrometry (RBS), X-ray diffraction, proton-induced X-ray emission, X-ray absorption spectroscopy (XAS) and time-of-flight secondary-ion mass spectrometry indicated negligible magnetic contaminants in the films. The presence of FM with concomitant large carrier densities was determined by a combination of superconducting quantum interference device magnetometry, electrical transport measurements, soft X-ray magnetic circular dichroism (SXMCD), XAS and optical magnetic circular dichroism, and was supported by first-principles calculations. SXMCD and XAS measurements revealed a 90 per cent contribution to FM from the Ti ions, and a 10 per cent contribution from the O ions. RBS/channelling measurements show complete Ta substitution in the Ti sites, though carrier activation was only 50 per cent at 5 per cent Ta concentration, implying compensation by cationic defects. The role of the Ti vacancy ( V Ti ) and Ti 3+ was studied via XAS and X-ray photoemission spectroscopy, respectively. It was found that, in films with strong FM, the V Ti signal was strong while the Ti 3+ signal was absent. We propose (in the absence of any obvious exchange mechanisms) that the localized magnetic moments, V Ti sites, are ferromagnetically ordered by itinerant carriers. Cationic-defect-induced magnetism is an alternative route to FM in wide-band-gap semiconducting oxides without any magnetic elements.
Publisher: American Physical Society (APS)
Date: 29-03-2010
Publisher: IEEE
Date: 10-2010
Publisher: American Physical Society (APS)
Date: 03-06-2013
Publisher: American Physical Society (APS)
Date: 08-11-2010
Location: United States of America
No related grants have been discovered for Kesong Yang.