利用時間解析磁光柯爾效應光譜研究受應力之La0.7Sr0.3MnO3薄膜磁化動力學

Abstract

鈣鈦礦錳錳氧化物La0.7Sr0.3MnO3在居禮溫度Tc = 380 K以下具有鐵磁金屬態。而在本文的實驗中，利用雷射蒸鍍系統分別在SrTiO3(100)、 LaAlO3(100)和NdGdO3(110)成長出受不同應變之La0.7Sr0.3MnO3薄膜。應變形態的不同可影響La0.7Sr0.3MnO3薄膜的磁各向異性，進而利用時間解析柯爾效應光譜來探測其光致磁化動力學，藉由分析柯爾旋轉角的變化，得到因薄膜不同的應變效應導致進動週期的改變與光致去磁化的時間，本文將對於所觀察到因應變效應而影響磁動力行為可能的機制進行討論。

Perovskite manganite La0.7Sr0.3MnO3 show the ferromagnetic metal phase below Tc = 380 K. In this work, the (001)-oriented La0.7Sr0.3MnO3 with various nominal strain state were deposited on SrTiO3(100), LaAlO3(100) and NdGdO3(110) substrates by pulsed laser deposition. The magnetic anisotropy may be change dependent on the type of strain. The photoinduced dynamics of magnetization is probed by Time-Resolved Magneto-Optical Kerr Effect Spectroscopy. Analyses based on the measured Kerr angle-change(ΔθK) curves revealed that while the period of the precession and photoinduced demagnetization time changes with the variation of the thin film strain effect. The possible mechanism for the observed strain effect on the dynamics of magnetization is discussed.