Heterogeneous magnetic state in nanocrystalline cupric oxide CuO / Yermakov A. Ye,Uimin M. A.,Korolyov A. V.,Mikhalev K. N.,Pirogov A. N.,Teplykh A. E.,Shchegoleva N. N.,Gaviko V. S.,Byzov I. V.,Maikov V. V. // PHYSICS OF THE SOLID STATE. - 2015. - V. 57, l. 2. - P. 296-308.

ISSN/EISSN:

1063-7834 / 1090-6460

Type:

Article

Abstract:

This paper presents the results of investigations of the structural state and magnetic properties of nanocrystalline cupric oxide samples with average particle sizes of approximately 40 and 13 nm, which were synthesized by the electric explosion and gas phase methods, respectively. The samples have been studied using X-ray diffraction, neutron diffraction, magnetic measurements, high-resolution transmission electron microscopy, and copper nuclear magnetic resonance. It has been shown that, in the initial state, regardless of the synthesis method, CuO nanoparticles are characterized by a heterogeneous magnetic state, i.e., by the existence of long-range antiferromagnetic order, spontaneous magnetization, especially at low temperatures, and paramagnetic centers in the material. The ferromagnetic contribution is probably caused by the formation of magnetic polaron states due to the phase separation induced in the system by excess charge carriers as a result of the existence of point defects (vacancies in the anion sublattice) in the nanocrystalline state. In this state, there is an inhomogeneously broadened nuclear magnetic resonance spectrum, which is a superposition of the spectrum of the initial antiferromagnetic matrix and the spectrum of ferromagnetically ordered regions. At high concentrations of ferromagnetically ordered regions, the antiferromagnetic matrix exhibits a nuclear magnetic resonance spectrum of CuO nanoparticles, predominantly from regions with the ferromagnetic phase. The appearance of magnetization can also be partly due to the frustration of spins in CuO, and this state is presumably localized near the most imperfect surface of the nanoparticles. The magnetic susceptibility of nanoparticles in the initial state in strong magnetic fields is significantly higher than that for the annealed samples, which, most likely, is associated with the influence of the high concentration of magnetic polarons. No correlation between the ferromagnetic contribution and the size of particles is found. In the CuO samples annealed at 400A degrees C in air, when the average size of CuO nanoparticles remains unchanged, the ferromagnetic contribution completely disappears, and the magnetic behavior of the nanoparticles becomes qualitatively similar to the magnetic behavior of bulk CuO.

Author keywords:

COPPER MONOXIDE; NIO NANOPARTICLES; NEUTRON-SCATTERING; PHASE-SEPARATION; EXCHANGE BIAS; DIFFRACTION; NMR; ANTIFERROMAGNETISM; SUSCEPTIBILITY; SEMICONDUCTOR

DOI:

10.1134/S1063783415020092

Web of Science ID:

ISI:000349970800014

Соавторы в МНС:

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Другие поля

Поле	Значение
Month	FEB
Publisher	MAIK NAUKA/INTERPERIODICA/SPRINGER
Address	233 SPRING ST, NEW YORK, NY 10013-1578 USA
Language	English
EISSN	1090-6460
Keywords-Plus	COPPER MONOXIDE; NIO NANOPARTICLES; NEUTRON-SCATTERING; PHASE-SEPARATION; EXCHANGE BIAS; DIFFRACTION; NMR; ANTIFERROMAGNETISM; SUSCEPTIBILITY; SEMICONDUCTOR
Research-Areas	Physics
Web-of-Science-Categories	Physics, Condensed Matter
Author-Email	yermakov@imp.uran.ru
ResearcherID-Numbers	Yermakov, Anatoly/J-5185-2013 Uimin, Mikhail/K-1319-2013 Pirogov, Alexander/K-8115-2013 Gaviko, Vasilii/K-4632-2013 Maikov, Vladislav/K-6628-2013 Щеголева, Нина/B-6589-2017 Alexander, Korolev/K-3036-2013 Mikhalev, Konstantin/K-3069-2013 Byzov, Ilya/J-7850-2013
ORCID-Numbers	Yermakov, Anatoly/0000-0001-6466-7064 Uimin, Mikhail/0000-0003-3906-8101 Pirogov, Alexander/0000-0001-7321-1245 Gaviko, Vasilii/0000-0002-9841-9293 Maikov, Vladislav/0000-0003-4028-4354 Alexander, Korolev/0000-0002-5104-3997 Mikhalev, Konstantin/0000-0001-5726-4427 Byzov, Ilya/0000-0003-1940-4892
Funding-Acknowledgement	Presidium of the Russian Academy of Sciences {[}12-P-234-2003]; Ural Branch of the Russian Academy of Sciences {[}13-24-010-UMA, 12-P-2-1019]; Russian Foundation for Basic Research {[}14-02-00032a, 14-03-00949]
Funding-Text	This study was supported by the Presidium of the Russian Academy of Sciences (program no. 12-P-234-2003), the Ural Branch of the Russian Academy of Sciences (project no. 13-24-010-UMA), and in part by the Russian Foundation for Basic Research (project nos. 14-02-00032a and 14-03-00949). The investigations were performed at the IVV-2M Neutron Materials Science Complex within the framework of the IMP program ``Potok{''} and supported by the Ural Branch of the Russian Academy of Sciences within the framework of the program ``Fundamental Problems of Physical and Engineering Sciences{''} (project no. 12-P-2-1019).
Number-of-Cited-References	44
Usage-Count-Since-2013	32
Journal-ISO	Phys. Solid State
Doc-Delivery-Number	CB9RT