Zhang Kunyan, Fu Chuliang, Kelly Shelly, Liang Liangbo, Kang Seoung-Hun, Jiang Jing, Zhang Ruifang, Wang Yixiu, Wan Gang, Siriviboon Phum, Yoon Mina, Ye Peide D, Wu Wenzhuo, Li Mingda, Huang Shengxi
Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Department of Chemistry, University of California, Berkeley, CA 94720, USA.
Sci Adv. 2025 Jan 10;11(2):eads4763. doi: 10.1126/sciadv.ads4763. Epub 2025 Jan 8.
Polarons, quasiparticles from electron-phonon coupling, are crucial for material properties including high-temperature superconductivity and colossal magnetoresistance. However, scarce studies have investigated polaron formation in low-dimensional materials with phonon polarity and electronic structure transitions. In this work, we studied polarons of tellurene, composed of chiral Te chains. The frequency and linewidth of the A phonon, which becomes increasingly polar for thinner tellurene, change abruptly for thickness below 10 nanometers, where field-effect mobility drops rapidly. These phonon and transport signatures, combined with phonon polarity and band structure, suggest a crossover from large polarons in bulk tellurium to small polarons in few-layer tellurene. Effective field theory considering phonon renormalization in the small-polaron regime semiquantitatively reproduces the phonon hardening and broadening effects. This polaron crossover stems from the quasi-one-dimensional nature of tellurene, where modulation of interchain distance reduces dielectric screening and promotes electron-phonon coupling. Our work provides valuable insights into the influence of polarons on phononic, electronic, and structural properties in low-dimensional materials.
极化子是电子 - 声子耦合产生的准粒子，对于包括高温超导和巨磁阻在内的材料特性至关重要。然而，很少有研究探讨具有声子极性和电子结构转变的低维材料中的极化子形成。在这项工作中，我们研究了由手性碲链组成的碲烯中的极化子。对于更薄的碲烯，A声子的频率和线宽的极性越来越大，在厚度低于10纳米时会突然变化，此时场效应迁移率会迅速下降。这些声子和输运特征，结合声子极性和能带结构，表明从块状碲中的大极化子到少层碲烯中的小极化子的转变。考虑小极化子区域声子重整化的有效场论半定量地再现了声子硬化和展宽效应。这种极化子转变源于碲烯的准一维性质，其中链间距离的调制降低了介电屏蔽并促进了电子 - 声子耦合。我们的工作为极化子对低维材料中的声子、电子和结构性质的影响提供了有价值的见解。
