Search for a quantum spin liquid in the Kitaev honeycomb lattice, alpha-RuCl3
Final Report Abstract
Throughout the funding periods, the most important scientific achievements are as follows. (1) Previously, we provided evidence for orbital-driven nematicity in FeSe. However, it was argued that orbital-driven nematic order is special in FeSe among Fe-based superconductors. In this work, we have investigated the nematic and magnetic properties in high-quality LaFeAsO single crystals and conclude that the leading instability for nematicity is identical for both FeSe and LaFeAsO, irrespective of whether long-range magnetic ordering occurs in the nematic state. (2) In a further work, published in "Nature Communications", we report the successful growth of homogeneous Na1−xLixFeAs single crystals and the investigation of their electronic phase diagram up to x = 0.1. Our data imply that the nature of a nematic state could vary depending on the underlying electronic structure. Furthermore, our rich phase diagram strongly suggests that the normal state of FeSCs from which superconductivity emerges is far more complex than previously known. (3) In another paper, we demonstrate that the superconducting transition temperature Tc increases in proportion to the strength of spin fluctuations, while it is independent of the nematic transition temperature Tnem. Our observation therefore directly implies that superconductivity in FeSe is essentially driven by spin fluctuations in the intermediate coupling regime, while nematic fluctuations have a marginal impact on Tc.
Publications
- Nature Communications 9, 2139 (2018)
S.-H. Baek et al.
(See online at https://doi.org/10.1038/s41467-018-04471-7) - Physical Review B 97, 180405(R) (2018)
J. M. Ok, S.-H. Baek et al.
(See online at https://doi.org/10.1103/PhysRevB.97.180405) - npj Quantum Materials 5, 8 (2020)
S.-H. Baek et al.
(See online at https://doi.org/10.1038/s41535-020-0211-y)
