Magneto-optical imaging of the magnetization process in colossal magnetoresisitive lanthanum manganite

Polyanskii, A; Wang, XL; Yao, QW; Dou, SX; Lin, ZW; Zhu, JG

Magneto-optical imaging of the magnetization process in colossal magnetoresisitive lanthanum manganite

Polyanskii, A Wang, XL Yao, QW Dou, SX Lin, ZW Zhu, JG

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Publication Type:: Journal Article
Citation:: Journal of Applied Physics, 2006, 99 (8)
Issue Date:: 2006-05-25

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Field	Value	Language
dc.contributor.author	Polyanskii, A	en_US
dc.contributor.author	Wang, XL	en_US
dc.contributor.author	Yao, QW	en_US
dc.contributor.author	Dou, SX	en_US
dc.contributor.author	Lin, ZW	en_US
dc.contributor.author	Zhu, JG https://orcid.org/0000-0002-9763-4047	en_US
dc.date.issued	2006-05-25	en_US
dc.identifier.citation	Journal of Applied Physics, 2006, 99 (8)	en_US
dc.identifier.issn	0021-8979	en_US
dc.identifier.uri	http://hdl.handle.net/10453/770
dc.description.abstract	To gain insight into the origin of the colossal reduction of resistance in response to magnetic field in colossal magnetoresistance manganite, the magnetic field induced transition in ferromagnetic La0.7 Ca0.3 Mn O3 was studied using a high-resolution magneto-optical imaging (MOI) technique. The MO images were captured in various magnetic fields over a wide temperature range for both highly dense samples with strong-link grain boundaries and porous samples with weak-link boundaries. Formation and evolution of magnetic domains as a function of field or temperature were clearly observed around and far below the Curie temperature TC =240 K. Ferromagnetic areas tend to grow to large sizes and finally join together at the expense of paramagnetic areas as the field increases or temperature decreases for strong-link samples. A sharp magnetoresistive transition is observed when the sample changes from a paramagnetic insulator to a metallic ferromagnetic phase in the vicinity of TC. In contrast, the porous samples showed magnetoresistance over a wide temperature range and exhibited a remarkable grain boundary related magnetization process in addition to magnetization within grains. A close correlation is found between the magnetization process observed by MOI and magnetoresistance measurements. Our MOI results indicate that the strong-link or weak-link grain boundaries are responsible, respectively, for magnetoresistance occurring either only in the vicinity of the ferromagnetic transition or over a very wide temperature range. © 2006 American Institute of Physics.	en_US
dc.relation.ispartof	Journal of Applied Physics	en_US
dc.relation.isbasedon	10.1063/1.2177393	en_US
dc.subject.classification	Applied Physics	en_US
dc.title	Magneto-optical imaging of the magnetization process in colossal magnetoresisitive lanthanum manganite	en_US
dc.type	Journal Article
utslib.citation.volume	8	en_US
utslib.citation.volume	99	en_US
utslib.for	0912 Materials Engineering	en_US
utslib.for	01 Mathematical Sciences	en_US
utslib.for	02 Physical Sciences	en_US
utslib.for	09 Engineering	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Electrical and Data Engineering
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Mechanical and Mechatronic Engineering
pubs.organisational-group	/University of Technology Sydney/Strength - CCET - Centre for Clean Energy Technology
pubs.organisational-group	/University of Technology Sydney/Strength - GEVI - Green Energy and Vehicle Innovations
utslib.copyright.status	closed_access
pubs.issue	8	en_US
pubs.publication-status	Published	en_US
pubs.volume	99	en_US

Abstract:

To gain insight into the origin of the colossal reduction of resistance in response to magnetic field in colossal magnetoresistance manganite, the magnetic field induced transition in ferromagnetic La0.7 Ca0.3 Mn O3 was studied using a high-resolution magneto-optical imaging (MOI) technique. The MO images were captured in various magnetic fields over a wide temperature range for both highly dense samples with strong-link grain boundaries and porous samples with weak-link boundaries. Formation and evolution of magnetic domains as a function of field or temperature were clearly observed around and far below the Curie temperature TC =240 K. Ferromagnetic areas tend to grow to large sizes and finally join together at the expense of paramagnetic areas as the field increases or temperature decreases for strong-link samples. A sharp magnetoresistive transition is observed when the sample changes from a paramagnetic insulator to a metallic ferromagnetic phase in the vicinity of TC. In contrast, the porous samples showed magnetoresistance over a wide temperature range and exhibited a remarkable grain boundary related magnetization process in addition to magnetization within grains. A close correlation is found between the magnetization process observed by MOI and magnetoresistance measurements. Our MOI results indicate that the strong-link or weak-link grain boundaries are responsible, respectively, for magnetoresistance occurring either only in the vicinity of the ferromagnetic transition or over a very wide temperature range. © 2006 American Institute of Physics.

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http://hdl.handle.net/10453/770