梯田式層狀結構鑭鈣錳氧化物薄膜穿隧光譜圖像之研究

Abstract

我們利用脈衝雷射蒸鍍法(PLD)在NdGaO3基板上成長梯田狀結構的龐磁阻錳氧化物La0.625Ca0.375MnO3薄膜，再以掃描穿隧式電子顯微鏡(STM)研究不同溫度樣品表面電子結構變化。我們的研究結果顯示樣品表面的傳導性分佈和表面結構有很大的關係，在層狀結構的交界處較易出現傳導性較佳的現象，隨溫度降低這情況趨於明顯，推測原因可能為受基板應力影響，交界處受應力較小所以較易形成大範圍傳噵性較佳的區域。這結果顯示相分離範圍的大小和基板應力分佈有很大關係。

The terrace-structure La0.625Ca0.375MnO3 thin films were grown on NdGaO3 substrates by Pulse Laser Deposition (PLD) system. Then we used scanning tunneling microscopy and spectroscopy to study the surfaces conductance images in various temperatures. We found that the inhomogeneous conductance appears to be intimately correlate with the surface structure. It appears that better conductivity is likely to occur near the boundary region at as the temperature is lowered, suggesting the prominent role played by the local strain variations. Moreover, it is also observed that the scale of phase separation is intimately correlated with the various strain distribution.