2026-09-24 合肥物質科学研究院（HFIPS）
Schematic 2D layered crystal structure of TlGaS2 (left panel). Temperature-dependent in-plane dielectric constant and image of the TlGaS2 single crystal (right panel). (Image by YIN Lihua)
＜関連情報＞
- https://english.hf.cas.cn/nr/rn/202609/t20260924_1201491.html
- https://journals.aps.org/prb/abstract/10.1103/82bg-5mt2
二次元層状構造における初期強誘電挙動と構造相転移TlG1S2 Incipient ferroelectric behavior and structural phase transitions in two-dimensional layered TlGaS2
A. D. Molchanova, L. H. Yin, L. P. Gao, W. H. Song, Y. P. Sun, K. R. Allahverdiyev, and M. N. Popova
Physical Review B Published: 4 September, 2026
DOI: https://doi.org/10.1103/82bg-5mt2
Abstract
The coexistence of out-of-plane and in-plane electric polarization is rare in two-dimensional (2D) ferroelectric materials, yet the two configurations offer distinct advantages for ferroelectric-based devices. Here, we report the coexistence of in-plane and out-of-plane incipient ferroelectricity, along with various phase transitions, in 2D van der Waals layered TlGaS2 single crystal. Detailed investigation of the incipient ferroelectric soft-mode behavior reveals a close correlation between the incipient ferroelectricity and the off-center displacement of Tl1+ ions with 62 lone pairs in TlGaS2. Anomalies near temperatures of about 75, 120, 180, and 220 K in infrared spectra, together with the absence of anomalies in the temperature-dependent specific heat, indicate the existence of local or weak long-range structural transitions in TlGaS2. Our results provide important experimental evidence for elucidating the phase transitions and coexistence of in-plane and out-of-plane incipient ferroelectricity in 2D layered TlGaS2.
