近日，日本东京大学的Etienne Janod&Shinichiro Iwai及其研究团队取得一项新进展。经过不懈努力，他们对莫特材料中由光致应变波驱动的绝缘体到金属跃迁的传播进行研究。相关研究成果已于2024年9月17日在国际知名学术期刊《自然—物理学》上发表。
该研究团队展示了这样一种应变波机制驱动了莫特材料V2O3颗粒薄膜中的超快绝缘体-金属相变。该研究的时间分辨光学反射率和X射线衍射测量结果显示，在绝缘体-金属相变之前，会发生逆铁弹性剪切，该剪切随压缩应变波的传播而传播。这些动力学过程分别受畴尺寸和薄膜厚度的控制。
这项研究结果阐明了颗粒薄膜中偏好的超快相变的形态条件，而这种相变在单晶中则会受到阻碍。所得的物理图像为量子材料，和未来基于莫特绝缘体的器件中的超快相变提供了见解。
据悉，超快光激发可在莫特绝缘体中产生内部压缩应力，从而导致自由表面产生应变波。这些光诱导的弹性波可触发材料中的相变。然而，一个包含声频尺度传播的相变动力学全面物理图像尚未建立。
附：英文原文
Title: Propagation of insulator-to-metal transition driven by photoinduced strain waves in a Mott material
Author: Amano, Tatsuya, Babich, Danylo, Mandal, Ritwika, Guzman-Brambila, Julio, Volte, Alix, Trzop, Elzbieta, Servol, Marina, Pastor, Ernest, Alashoor, Maryam, Larsson, Jrgen, Jurgilaitis, Andrius, Pham, Van-Thai, Kroon, David, Ekstrm, John Carl, Ahn, Byungnam, Mariette, Cline, Levantino, Matteo, Kozhaev, Mikhail, Tranchant, Julien, Corraze, Benoit, Cario, Laurent, Dolatabadi, Mohammad, Phuoc, Vinh Ta, Sopracase, Rodolphe, Guillon, Mathieu, Itoh, Hirotake, Kawakami, Yohei, Nakamura, Yuto, Kishida, Hideo, Cailleau, Herv, Lorenc, Maciej, Iwai, Shinichiro, Janod, Etienne
Issue&Volume: 2024-09-17
Abstract: Ultrafast photoexcitation can generate internal compressive stress in Mott insulators that lead to strain waves from free surfaces. These photoinduced elastic waves can trigger phase transitions in materials. However, a comprehensive physical picture of the phase transformation dynamics that includes acoustic-scale propagation has not yet been developed. Here we demonstrate that such a strain-wave mechanism drives the ultrafast insulator-to-metal phase transition in granular thin films of the Mott material V2O3. Our time-resolved optical reflectivity and X-ray diffraction measurements reveal that an inverse ferroelastic shear occurs before the insulator-to-metal transition, which propagates in the wake of a compressive strain wave. These dynamics are governed by the domain size and film thickness, respectively. Our results clarify the morphological conditions for the ultrafast phase transition that is favoured in granular thin films and hindered in single crystals. The resulting physical picture sheds light on the ultrafast phase transitions in quantum materials and future devices based on Mott insulators.
DOI: 10.1038/s41567-024-02628-4
Source: https://www.nature.com/articles/s41567-024-02628-4