利用射頻磁控濺鍍法，我們成功的成長出取向性佳的La0.85Zr0.15MnO3薄膜於STO及MgO基板上。在經過適當的退火補氧後，LZMO/STO與LZMO/MgO薄膜皆呈現出絕緣-金屬相轉變的特性。在應力效應的影響下，LZMO/STO薄膜c軸長度較LZMO/MgO長。受晶格不匹配度的影響，相對於LZMO/STO薄膜而言，LZMO/MgO的晶粒較小、晶界較多，使得殘餘電阻值較大、磁轉變溫區較寬、矯頑磁場較大。在磁性方面，LZMO/STO無論是軸向或平面上的鐵磁性皆較LZMO/MgO強，但磁異向性較弱。另外，LZMO/MgO受應力效應的影響而呈現出A-type反鐵磁的特性。藉由MFM、SEPM及C-AFM量測的結果，在LZMO/Nb-STO薄膜中，具有鐵磁性的區域，其導電性較佳。從實驗結果發現，受磁異向性強弱的影響，當磁異向性弱時，電阻與角度(薄膜c軸與外加磁場間的夾角,θ)間的關係函數為sin2(θ)或是cos2(θ)；當磁異向性強時，則為sin4(θ)或是cos4(θ)。受應力效應的影響，在錳離子位置上能量較穩定的軌域(3dx2-y2、3d3z2-r2)也會有所不同，進而影響薄膜c軸與a-b平面上氧2p與錳3d軌域間的混成，導致藉由短程自旋相關所形成的偏極子在c軸與a-b平面上的耦合強度也不同，使得傳導載子的有效質量產生異向性，而在電阻與角度間的關係表現出正弦函數與餘弦函數兩種不同的趨勢。異向性磁阻比率在變溫及變磁場的情形下，依據我們以古典圖像自行推導的定性公式及實驗結果來看，異向性磁阻比率增加的原因是受系統磁性增強的影響；受偏極子狀態會隨系統磁性增強而穩定並增加傳導載子的有效質量，因而降低了異向性磁阻比率。 La0.85Zr0.15MnO3 (LZMO) epitaxial films were successfully grown on SrTiO3 (STO) (001) and MgO (001) substrates by an off-axis rf sputtering system. It is found that the grain size of the tensile-strained LZMO/MgO film is smaller than that of the compressive-strained LZMO/STO film, giving rise to more grain boundaries, larger residual resistance and coercive field for LZMO/MgO film compared with LZMO/STO film. In addition, the magnetic anisotropy of films investigated is moderately tuned by strain-induced orbital stability of 3dx2-y2 and 3d3z2-r2. As a result, the compressive-strained LZMO/STO film displays in-plane and out-of-plane ferromagnetic couplings between near-neighbor Mn spins, whereas the tensile-strained LZMO/MgO film exhibits a weaker in-plane ferromagnetic coupling and possible out-of-plane antiferromagnetic coupling between Mn ions. More importantly, the angular dependence of the anisotropic magnetoresistance (AMR), defined as (Rmax-Rmin)/Rmin, It appears that the sin2(θ) (θ is angle between the applied magnetic field and the c-axis of the film) and cos2(θ) dependence dominates near TMI at which films studied have relatively weak magnetic anisotropy. Whereas the sin4(θ) and cos4(θ) dependence plays an important role in AMR at low temperature regime where films studied have relatively strong magnetic anisotropy. Based upon extensive analysis of data, the observed sine and cosine dependent AMR is qualitatively associated with effective mass anisotropy arising from short-range spin correlation induced by strain. More precisely, sine dependent dominates in the case of meffc > meffab where the occupancy of 3d3z2-r2 is greater than that of 3dx2-y2 and cosine dependent prevails in the case of meffab > meffc where the occupancy of 3dx2-y2 is greater than that of 3d3z2-r2. These intriguing findings unambiguously dominate that charge, spin, and lattice degrees of freedom in the strained LZMO epitaxial films are strongly correlated.
