TmMnO3奈米粒子對成長於鈦酸鍶基板上YBa2Cu3O7-δ薄膜之磁通釘扎效應研究

Abstract

本論文旨在探討以銩錳氧奈米粒子對鈦酸鍶基板進行表面修飾時，對成長於其上之釔鋇銅氧薄膜的釘扎機制造成的影響。本實驗採用脈衝雷射蒸鍍系統在鈦酸鍶(100)基板上成長不同密度之銩錳氧奈米粒子後，再沉積c軸向之釔鋇銅氧薄膜於其上，並透過電阻-溫度量測系統及超導量子干涉儀瞭解成長於薄膜/基板接面處之銩錳氧奈米粒子對薄膜超導特性造成的影響。結果顯示，成長於較高密度銩錳氧奈米粒子上之釔鋇銅氧薄膜在臨界電流密度及釘扎力密度上皆有顯著的成長；反之，成長於較低密度銩錳氧奈米粒子上之釔鋇銅氧薄膜則與成長於未經表面處理之基板上時表現相當，說明了銩錳氧奈米粒子對釔鋇銅氧薄膜中的釘扎效應的增強有其臨界密度門檻，而這項提升則可能為銩錳氧奈米粒子在薄膜中所造成的缺陷對磁通渦旋線形成釘扎的結果。

The c-axis-oriented YBa2Cu3O7-δ (YBCO) thin films were deposited on bare and TmMnO3 (TMO) nanoparticle decorated SrTiO3 (STO) substrates by pulsed laser deposition. The effect of antiferromagnetic TMO nanoparticles, present at the interface between film and substrate, on the superconducting properties of YBCO thin film has been investigated by LCR meter and SQUID. The YBCO thin film on decorated STO substrate with high-density TMO nanoparticles shows significant improvement in the critical current density and pinning force density as compared to the YBCO thin film deposited on the decorated STO substrate with low-density TMO nanoparticles and bare substrate. This reveals that the vortex pinning by the present of TMO nanoparticles, which may induce extended defects along the c-axis, only occurs when the density of TMO nanoparticles exceeds certain threshold condition.