Abstract
A many-body quantum system on the verge of instability between two competing ground states may exhibit quantum-critical phenomena1,2, as has been intensively studied for magnetic systems. The Mott metal–insulator transition3, a phenomenon that is central to many investigations of strongly correlated electrons, is also supposed to be quantum critical, although this has so far not been demonstrated experimentally. Here, we report experimental evidence for the quantum-critical nature of the Mott instability, obtained by investigating the electron transport of three organic systems with different ground states under continuously controlled pressure. The resistivity obeys the material-independent quantum-critical scaling relation bifurcating into a Fermi liquid or Mott insulator, irrespective of the ground states. Electrons on the verge of becoming delocalized behave like a strange quantum-critical fluid before becoming a Fermi liquid.
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(δP, T) of κ-Cu2(CN)3 measured from the metal–insulator crossover line against δP = P − Pc(T).
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Acknowledgements
We would like to thank V. Dobrosavljević, N. Nagaosa, H. Oike and T. Itou for fruitful discussions. This work was supported in part by JSPS KAKENHI under Grant Nos 20110002, 25220709 and 24654101, and the US National Science Foundation under Grant No. PHYS-1066293 and the hospitality of the Aspen Center for Physics.
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T.F. and K.K. designed the experiments. T.F. performed the experiments and analysed the data. T.F. and K.K. interpreted the data. K.M., H.T. and R.K. grew the single crystals for the study. T.F. wrote the manuscript with the assistance of K.M. and K.K. K.K. headed this project.
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Furukawa, T., Miyagawa, K., Taniguchi, H. et al. Quantum criticality of Mott transition in organic materials. Nature Phys 11, 221–224 (2015). https://doi.org/10.1038/nphys3235
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DOI: https://doi.org/10.1038/nphys3235
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