Abstract
A counterintuitive enhancement of quantum fluctuation with larger spins, together with a few physical phenomena, is discovered in studying the recently observed emergent magnetism in high-temperature superconductor FeSe under pressure. Starting with an experimental crystalline structure from our high-pressure x-ray refinement, we theoretically analyze the stability of the magnetically ordered state with a realistic spin-fermion model. We find, surprisingly, that in comparison with magnetically ordered Fe pnictides, the larger spins in FeSe suffer even stronger long-range quantum fluctuations that diminish their ordering at ambient pressure. This fail-to-order quantum spin-liquid state then develops into an ordered state above 1 GPa due to weakened fluctuation accompanying the reduction of anion height and carrier density. The ordering further benefits from the ferro-orbital order and shows the observed enhancement around 1 GPa. We further clarify the controversial nature of magnetism and its interplay with nematicity in FeSe in the same unified picture for all Fe-based superconductors. In addition, the versatile itinerant carriers produce interesting correlated metal behavior in a large region of phase space. Our paper establishes a generic exotic paradigm of stronger quantum fluctuation with larger spins that complements the standard knowledge of insulating magnetism.
| Original language | English |
|---|---|
| Article number | 033115 |
| Journal | Physical Review Research |
| Volume | 4 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jul 2022 |
Funding
We thank V Dobrosavljevic, O Vafek, and Guangming Zhang for useful discussions. Y.T., T.Z., and W.K. acknowledge support from National Natural Science Foundation of China No. 12042507 and Innovation Program for Quantum Science and Technology No. 2021ZD0301900. Y.T. and D.-X.Y. acknowledge support from NKRDPC-2017YFA0206203, NKRDPC-2018YFA0306001, NSFC-11974432, NSFC-92165204, GBABRF-2019A1515011337, and Leading Talent Program of Guangdong Special Projects (201626003). Portions of this research used resources at the Spallation Neutron Source, as well as the Advanced Photon Source, both user facilities operated by the Oak Ridge National Laboratory, and the Argonne National Laboratory, respectively, for the Office of Science of the U.S. Department of Energy (DOE). Work at Michigan State University was supported by the National Science Foundation under Award No. DMR-1608752 and start-up funds from Michigan State University. Work at Tulane University was supported by the U.S. Department of Energy (DOE) under EPSCOR Grant No. DE-SC0012432 with additional support from the Louisiana Board of Regents (support for material synthesis).