npj Computational Materials ( IF 9.7 ) Pub Date : 2020-04-08 , DOI: 10.1038/s41524-020-0303-z Xue-Peng Wang , Xian-Bin Li , Nian-Ke Chen , Junhyeok Bang , Ryky Nelson , Christina Ertural , Richard Dronskowski , Hong-Bo Sun , Shengbai Zhang
Recently, all-optical memory and optical-computation properties of phase-change materials are receiving intensive attention. Because writing/erasing information in these devices is usually achieved by laser pulses, the interaction between the laser and the phase-change materials becomes a key issue for such new applications. In this work, by a time-dependent density-functional theory molecular-dynamics study, the physics underlying the optical excitation induced amorphization of Sc-Sb-Te is revealed, which goes back to superatom-like Sc-centered structural motifs. These motifs are found to be still robust under the excitation. A selected occupation of the Sc d-t2g orbitals (as a result of optical excitation) leads to a significant change of Sc-centered bond angles. In addition, the especially weak Sb-Te bonds next to the Sc motifs are further diminished by excitations. Therefore, the Sc-centered motifs can promote breaking, switching, and reforming of the surrounding Sb-Te network and, therefore, facilitate the amorphization of Sc-Sb-Te. The study shows the unique role of Sc-centered motifs in optically induced phase transition, and displays potential applications of Sc-Sb-Te alloys in optical memory/computation.
中文翻译:
时变密度泛函理论在光激发下Sc-Sb-Te合金非晶化的分子动力学研究
近来,相变材料的全光存储和光学计算特性受到广泛关注。因为在这些设备中写入/擦除信息通常是通过激光脉冲实现的,所以激光器与相变材料之间的相互作用成为此类新应用的关键问题。在这项工作中,通过基于时间的密度泛函理论分子动力学研究,揭示了光激发诱导的Sc-Sb-Te非晶化的物理基础,这可以追溯到超原子状的以Sc为中心的结构图案。发现这些图案在激发下仍然很坚固。Sc d - t 2g的选定职业轨道(作为光激发的结果)导致以Sc为中心的键角发生显着变化。另外,通过激发进一步减少了Sc基序旁边特别弱的Sb-Te键。因此,以Sc为中心的基序可以促进周围Sb-Te网络的断裂,切换和重整,从而促进Sc-Sb-Te的非晶化。该研究显示了以Sc为中心的基序在光学诱导的相变中的独特作用,并显示了Sc-Sb-Te合金在光学存储/计算中的潜在应用。