Abstract
Employing inelastic x-ray scattering and neutron scattering techniques, we observed nematic and magnetic phase transitions with distinct characters in K5Fe4Ag6Te10. Upon cooling, the nematic order undergoes a strongly first-order phase transition followed by a magnetic transition at TN≈34.7K that is consistent with a second-order transition. The temperature difference between these two phase transitions is ∼1.0(8) K. The observed phenomenon can be attributed to a distinctive first-order preemptive Ising-nematic transition, a characteristic unique to a quasi-two-dimensional scenario marked by strong out-of-plane spatial anisotropy due to weak coupling. Our studies establish K5Fe4Ag6Te10 as the first material in the family of iron pnictides and chalcogenides that possesses a nematic tricritical point preceding the magnetic one upon decreasing nematic coupling.
| Original language | English |
|---|---|
| Article number | 224103 |
| Journal | Physical Review B |
| Volume | 111 |
| Issue number | 22 |
| DOIs | |
| State | Published - Jun 1 2025 |
Funding
The work at UC Berkeley and LBNL was funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Material Sciences and Engineering Division under Contract No. DE-AC02-05-CH11231 (Quantum Materials program KC2202). A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The synchrotron radiation experiments were performed at BL35XU of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) under Proposal No. 2023B1501. The work at Beijing Normal University is supported by the Fundamental Research Funds for the Central Universities (Grant No. 2243300003). The work at Zhejiang University is supported by the National Natural Science Foundation of China (No. 12350710785 and No. 12274363), and the Fundamental Research Funds for the Central Universities (Grant No. 226-2024-00068).