Abstract
Quantum materials that are found on the verge of structural, magnetic, and electronic instabilities are deep reservoirs for exotic phenomena. Our criteria to study the reported Ln5Ru6Sn18(Ln = Gd, Tb) are guided by the tolerance factor for Remeika phases─a class of intermetallic compounds with the general formula A3M4X13(where A = rare-earth element, M = transition metal, and X = tetrel), which can be viewed as structural analogues of pseudoperovskites (4 × ABX3), with one of the tetrel atoms occupying the A-site. We have grown single crystals, up to 0.5 cm on the largest facet, of Gd5Ru6Sn18(a = 13.8052(12) Å) and Tb5Ru6Sn18(a = 13.7825(9) Å), which we expect to be on the verge of a formation instability. Bulk magnetic, heat capacity, and electrical transport measurements reveal unusual behavior that originates from the trivalent Gd and Tb ions, with deviations from typical metallic behavior and magnetic ordering that is short-range or disrupted in some other way. To better understand these phenomena, single-crystal neutron diffraction is investigated, which reveals short-range correlations among the partially occupied Tb and Sn sublattices, with 3D-ΔPDF analysis supporting direction-dependent local order. Taken together, these measurements show the utility of using tolerance factors in identifying materials that are likely to exhibit complex phenomena and uncover environments where a formation instability may strongly impact emergent bulk magnetic and electronic phenomena.
| Original language | English |
|---|---|
| Pages (from-to) | 9014-9024 |
| Number of pages | 11 |
| Journal | Chemistry of Materials |
| Volume | 37 |
| Issue number | 21 |
| DOIs | |
| State | Published - Nov 11 2025 |
Funding
J.Y.C. and A.D.M. acknowledge support from DOE-DE-SC0022854, as well as Welch AA-2056-20240404, for partial funding of this work. R.E.B. acknowledges support by the University of California, Santa Cruz through startup funds, as well as a portion of this work being performed at the National High Magnetic Field Laboratory, with the National Science Foundation Cooperative Agreement No. DMR-2128556 and the State of Florida support. This research was supported in part by an appointment to the Oak Ridge National Laboratory GRO Program, sponsored by the U.S. Department of Energy and administered by the Oak Ridge Institute for Science and Education. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory as part of the Graduate Research Program at ORNL. The beam time was allocated to POWGEN on proposal number IPTS-34807. B.S. acknowledges the support of the NHML User Collaboration Grant Program (UCGP). The authors acknowledge Dr. Kaya Wei and Dr. Feng Ye for their helpful discussions.