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Low-spin S=1/2 ground state of the Cu trimers in the paper-chain compound Ba3Cu3In4O12статья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
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Web of Science
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Gippius A.A., Gervits N.E., Tkachev A.V., Maslova I.S., Volkova O.S., Vasiliev A.N., Buttgen N., Kraetschmer W., Moskvin A.S.
- Журнал: Physical Review B
- Том: 86
- Год издания: 2012
- Издательство: American Physical Society
- Местоположение издательства: United States
- Первая страница: 155114
- Последняя страница: 155114
- DOI: 10.1103/PhysRevB.86.155114
- Аннотация: The magnetic ground states of the isostructural paper-chain compounds Ba3Cu3In4O12 and Ba3Cu3Sc4O12 were recently found to be ordered antiferromagnetically (AFM), while both quantum magnets reveal positive asymptotic Curie-Weiss temperatures suggestive of ferromagnetic (FM) interactions at high temperatures. Due to the AFM-FM competition the saturation magnetization in both compounds is reached already in modest magnetic fields with a nontrivial succession of two spin-flop and two spin-flip-like transitions in Ba3Cu3In4O12. We argue that the paper-chains in both compounds can be described as a system of CuI-2CuII trimers with a low-spin S=1/2 ground state which implies a nonmagnetic spin-singlet CuII dimer state and a spin-polarized CuI ion. To validate the model we performed extensive nuclear resonance—nuclear quadrupole resonance-nuclear magnetic resonance (NQR-NMR)—measurements in Ba3Cu3In4O12. Two different types of 63,65Cu nuclear resonance spectra were observed in the magnetically ordered state at zero external magnetic field: (i) a pure NQR spectrum in the frequency range of 24–30 MHz and (ii) a zero-field NMR spectrum in the frequency range of 50–65 MHz. This result unambiguously indicates that one of the two types of copper ions in Ba3Cu3In4O12 is in a nonmagnetic spin state below TN. It provides a unique criterion to test any theoretical model describing the ground-state spin structure in Ba3Cu3In4O12 . We attribute the pure NQR spectrum to CuII ions forming nonmagnetic spin-singlet 2CuII dimers and the zero-field NMR spectrum to spin-polarized CuI ions. Both NQR and zero-field NMR spectra point to an existence of at least two nonequivalent sets of the copper trimers, probably due to displacements of the CuI ions along the cavity in the c direction.
- Добавил в систему: Волкова Ольга Сергеевна