鈣鈦礦氧化物之兆赫聲學

Terahertz Acoustics of Perovskite Oxides

我們利用時域激發-探測光譜技術研究銥酸鍶/鈦酸鍶及釕酸鍶/鈦酸鍶超晶格的兆赫聲學。樣品制備選擇使用脈衝雷射沉積法，因其具有成長高品質的晶體能力還有精準控制蒸鍍厚度達到數個分子層的優點，制備而成的超晶格樣品可產生近乎單頻的兆赫聲波。本文透過實驗與模擬方式研究0.5-1兆赫頻率的聲學聲子動態行為及其平均自由路徑，演示同調控制改變同調聲子的振幅與相位，並且比較釕酸鍶與銥酸鍶兩者的音波轉換效率。

Terahertz acoustics in SrIrO3/SrTiO3 and SrRuO3/SrTiO3 superlattices were investigated by using time-domain pump-probe spectroscopy. By using pulse laser deposition, superlattices of high quality with thicknesses down to several monolayers can be fabricated and quasi-monochromatic acoustic phonons in THz regime can be realized. In our study, the dynamics and mean-free-path of 0.5-1 THz acoustic phonons were investigated. Coherent control of acoustic phonons was demonstrated, and the manipulation of their amplitudes and phases was achieved. In addition, the optoacoustic conversion efficiency of SrRuO3 and SrIrO3 were compared.