近日，加拿大不列颠哥伦比亚大学Ismail El Baggari团队报道了量子准电SrTiO₃纳米级极性结构的成像。相关论文发表在2026年7月22日出版的《自然》杂志上。

在向铁电相变冷却的过程中，集体原子运动（声子）会减慢（软化），直至形成静态原子位移图案，从而在整个材料中产生自发极化。然而，在钛酸锶（SrTiO₃）等量子顺电体中，由于离子位置持续存在的量子涨落，长程铁电序在低温下并不发展。在SrTiO₃中，量子顺电性出现在Tq ≈ 40 K以下，并伴随有异常的声子动力学行为：横向声学声子模在有限波矢处发生部分软化，暗示纳米尺度上存在调制态。然而，尽管经过数十年的研究，SrTiO₃在低温下的精确实空间结构仍未得到解决。

研究组利用低温扫描透射电子显微镜，直接成像了SrTiO₃薄片在低至20 K温度下的极性结构。高分辨率成像揭示了一个空间涨落的纳米畴景观。在大约105 K以下，短程极性畴首先自组织成延伸数十纳米的周期性结构；然而，当进入Tq以下的量子顺电区域后，该过程发生逆转，周期性有序的极性纳米畴碎裂成更小的团簇。SrTiO₃中的量子顺电性是其诸多显著性质的基础，包括高介电常数、近铁电性、多铁性以及非常规超导电性。该可视化结果表明，这些现象可能与低温下极性纳米畴的复杂有序化和无序化过程有关。

附：英文原文

Title: Imaging of nanoscale polar textures in quantum paraelectric SrTiO3

Author: Zhang, Yang, Sung, Suk Hyun, Agarwal, Nishkarsh, Gates, Maya, Li, Cong, Yu, Pu, Hovden, Robert, El Baggari, Ismail

Issue&Volume: 2026-07-22

Abstract: When cooling towards a ferroelectric phase transition, collective atomic motions (phonons) slow down (soften) until a static atomic displacement pattern forms, giving rise to spontaneous polarization throughout the material1. However, in quantum paraelectrics such as strontium titanate (SrTiO3), long-range ferroelectric order does not develop at low temperatures due to persistent quantum fluctuations of ionic positions2,3. In SrTiO3, quantum paraelectricity emerges below Tq≈40K refs. 4,5,6 and is preceded by anomalous phonon dynamics: a transverse acoustic phonon mode partially softens at a finite wavevector, hinting at a modulated state at the nanoscale7,8,9,10,11,12. The precise real-space structure of SrTiO3 at low temperature, however, has remained unresolved despite decades of study. Here we directly image the low-temperature polar structure of a SrTiO3 lamella using cryogenic scanning transmission electron microscopy down to 20K. High-resolution imaging reveals a spatially fluctuating landscape of nanoscale domains. Below about 105K, short-range polar domains initially self-organize into a periodic structure extending over tens of nanometres; however, upon entering the quantum paraelectric regime below Tq, the process reverses and the periodically ordered polar nanodomains fragment into smaller clusters. Quantum paraelectricity in SrTiO3 underlies remarkable properties, including large dielectric permittivity13,14, proximity to ferroelectricity15,16, multiferroicity17 and unconventional superconductivity18,19,20. Our visualizations suggest that these phenomena may be linked to complex ordering and disordering of polar nanodomains at low temperature.

DOI: 10.1038/s41586-026-10823-x

Source: https://www.nature.com/articles/s41586-026-10823-x