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2018/9/8

Observing quantum vibrations of insulators, discovering unprecedented electronic states, Kyoto University, etc.

University Journal Online Editorial Department

　The research group of Kyoto University, Ibaraki University and others observed for the first time the phenomenon (quantum vibration) in which the electrical resistance and magnetic susceptibility vibrate with a magnetic field in a strong magnetic field in the itterbium 12 boro compound, which is an insulator that originally does not allow electrons to flow.Quantum oscillation is a phenomenon normally observed only in metals that carry electricity, which indicates the possibility of realizing an unprecedented electronic state that cannot be said to be a metal or an insulator in ytterbium 12 boride.

　The simplest and most accurate answer to the question "what is metal" is "substance with Fermi surface".The Fermi surface is a curved surface that forms the boundary between a state occupied by electrons and a state not occupied by all electrons when all the electrons are packed from the low energy state of the momentum vector space according to the Fermi statistics shown by the electrons.

　The most direct indication of the existence of the Fermi surface is "quantum vibration" in which electrical resistance and magnetization periodically move with changes in the external magnetic field in a strong magnetic field.It was a common wisdom in physics that the observation of quantum oscillations indicates the existence of the Fermi surface, that is, the realization of a metallic state.

　Recently, however, the quantum motion of magnetization was observed in the samarium 6 boride, which is one of the substances called Kondo insulator, even though it is an insulator, and it attracted a great deal of attention.Therefore, this research group conducted research on another Kondo insulator, ytterbium 12 boride.

　As a result, in the high-sensitivity magnetization measurement and precision electrical resistance measurement conducted at the National Institute of Strong Magnetic Fields, not only magnetization but also quantum vibration in electrical resistance was observed.Observation of such "quantum vibration of insulator" is unprecedented and is a result that overturns the conventional wisdom.

　With this research as an opportunity, new developments in insulators are expected.

Paper information:[Science] Quantum Oscillations of Electrical Resistivity in an Insulator

Kyoto University

Foster a free academic style based on the spirit of "self-respect for self-weight" and open up a world of creative learning.

With the motto of self-study, we will continue to maintain a free academic style that is not bound by common sense, and develop human resources who have both creativity and practical ability.We provide an inclusive learning space that allows for diverse and hierarchical choices so that students themselves can choose a solid future through valuable trial and error. […]

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Ibaraki University

Rooted in the land of Ibaraki, our goal is to contribute to a sustainable society and continue to produce excellent human resources.

Ibaraki University was established in 1949 (Showa 24) by integrating Mito High School, Ibaraki Normal School, Ibaraki Youth Normal School, and Taga Technical College.As a community-based university, we aim to contribute to the promotion of local education, research, art, culture, and industry, and to continue to produce talented human resources in the local and international communities […].

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