DocumentCode :
1869
Title :
Defect-Induced Room-Temperature Ferromagnetism in 
Nanowires Controlled by UV Light Irradiation
Author :
Bhaumik, Sudipta ; Sinha, Arun Kumar ; Ray, Samit K. ; Das, Amal K.
Author_Institution :
Dept. of Phys. & Meteorol., IIT Kharagpur, Kharagpur, India
Volume :
50
Issue :
5
fYear :
2014
fDate :
May-14
Firstpage :
1
Lastpage :
6
Abstract :
Nonferromagnetic SnO2 nanowires show ferromagnetism at room temperature, which is significantly enhanced upon irradiation by ultraviolet (UV) light of wavelength 365 nm. The structural characterizations on as-grown, UV-irradiated, and O2-annealed samples show no measurable difference in X-ray diffraction profiles and field-emission scanning and transmission electron microscopy images. But optical absorption, photoluminescence, and X-ray photoelectron spectroscopy reveal a significant effect of UV irradiation and establish a remarkable enhancement of O vacancies in SnO2 nanowires upon UV light irradiation, which diminishes after annealing in the presence of O2 gas. The as-grown and O2-annealed nanowires show weak ferromagnetism at room temperature, but the UV-irradiated nanowires show strong ferromagnetism. The origin of such ferromagnetism in pure (undoped) SnO2 is attributed to the presence of oxygen vacancies, which is tunable externally using UV irradiation.
Keywords :
X-ray diffraction; X-ray photoelectron spectra; absorption coefficients; annealing; coercive force; ferromagnetism; field emission electron microscopy; nanofabrication; nanowires; oxygen; photoluminescence; remanence; scanning electron microscopy; semiconductor growth; semimagnetic semiconductors; tin compounds; ultraviolet radiation effects; O2; SnO2; UV light irradiation; UV-irradiated nanowires; X-ray diffraction profiles; X-ray photoelectron spectroscopy; annealing; defect-induced ferromagnetism; field-emission scanning electron microscopy images; nonferromagnetic nanowires; optical absorption; oxygen vacancies; photoluminescence; structural characterizations; temperature 293 K to 298 K; transmission electron microscopy images; ultraviolet light irradiation; wavelength 365 nm; Annealing; Educational institutions; Lattices; Microscopy; Nanowires; Photonic band gap; Radiation effects; ${rm SnO}_{2}$ nanowires; Oxygen vacancy; SnO2 nanowires; UV light irradiation; oxygen vacancy; room temperature ferromagnetism; room-temperature ferromagnetism;
fLanguage :
English
Journal_Title :
Magnetics, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9464
Type :
jour
DOI :
10.1109/TMAG.2013.2292575
Filename :
6675871
Link To Document :
