Disturbance-resistant quantum liquid state discovered in copper-oxide magnetic body

Disturbance-resistant quantum liquid state discovered in copper-oxide magnetic body

May 4, 2012

NAKATSUJI Satoru, Associate Professor, Institute for Solid State Physics of the University of Tokyo has discovered  a new disturbance-resistant quantum liquid state in a copper-oxide magnetic body in cooperation with researchers at Nagoya University, Center for Quantum Science and Technology under Extreme Conditions, Osaka University , California State University, Japan Atomic Energy Agency, University of the Ryukyus, Bandung Institute of Technology, National Institute of Standards and Technology, University of Maryland, and Johns Hopkins University.

Up to the present, the quantum liquid state that develops within magnetic bodies has been considered sensitive to disturbances. A new quantum liquid state in which, when spin and orbit are arranged in a specific pattern, its symmetric property is kept and remains liquid at lower temperatures has been drawing attention and been studied around the world. However, this spin-orbit liquid state is known to be unstable and it has been thought that it transits into orbital ordering due to disturbances and/or changes in magnetized bodies. This group discovered a new quantum liquid state that can be achieved by controlling the spin-orbit cooperative phenomena of the electrons of copper atoms.
Positive ions in solid substances has a property to distort the electron cloud of the negative ion in order to lower its electronic energy (Jahn-Teller effect). Copper ion is a typical example and it has been thought that, this distortion, the Jahn-Teller transition, is shown in cuprates.
Ba3CuSb2O9 that the group has focused on was found to be the first example that does not undergo a cooperative Jahn-Teller transition down to low temperature and spin's liquid state remains at very cold temperatures. The spin achieved in this way was found to be disturbance-resistant. This is thought to be a local spin resonance state produced by spin-orbit cooperative phenomena. The experimental results indicate that the newly discovered phenomenon constitutes a very disturbance-resistant quantum liquid state, the understanding of which is expected to serve as a guideline for future substance/material developments.

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Figure 1

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Figure 2

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Figure 3

To learn more about this exciting and ground-breaking discovery, please read the full research report entitled " Spin-Orbital Short-Range Order on a Honeycomb-Based Lattice " at this page at the Science website.

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