Zurauskiene Nerija, Stankevic Voitech, Kersulis Skirmantas, Vagner Milita, Plausinaitiene Valentina, Dobilas Jorunas, Vasiliauskas Remigijus, Skapas Martynas, Koliada Mykola, Pietosa Jaroslaw, Wisniewski Andrzej
Center for Physical Sciences and Technology, 10257 Vilnius, Lithuania.
Faculty of Electronics, Vilnius Gediminas Technical University, 03227 Vilnius, Lithuania.
Sensors (Basel). 2022 May 25;22(11):4004. doi: 10.3390/s22114004.
The results of colossal magnetoresistance (CMR) properties of La1-xSrxMnyO3 (LSMO) films grown by the pulsed injection MOCVD technique onto an Al2O3 substrate are presented. The grown films with different Sr (0.05 ≤ x ≤ 0.3) and Mn excess (y > 1) concentrations were nanostructured with vertically aligned column-shaped crystallites spread perpendicular to the film plane. It was found that microstructure, resistivity, and magnetoresistive properties of the films strongly depend on the strontium and manganese concentration. All films (including low Sr content) exhibit a metal−insulator transition typical for manganites at a certain temperature, Tm. The Tm vs. Sr content dependence for films with a constant Mn amount has maxima that shift to lower Sr values with the increase in Mn excess in the films. Moreover, the higher the Mn excess concentration in the films, the higher the Tm value obtained. The highest Tm values (270 K) were observed for nanostructured LSMO films with x = 0.17−0.18 and y = 1.15, while the highest low-field magnetoresistance (0.8% at 50 mT) at room temperature (290 K) was achieved for x = 0.3 and y = 1.15. The obtained low-field MR values were relatively high in comparison to those published in the literature results for lanthanum manganite films prepared without additional insulating oxide phases. It can be caused by high Curie temperature (383 K), high saturation magnetization at room temperature (870 emu/cm3), and relatively thin grain boundaries. The obtained results allow to fabricate CMR sensors for low magnetic field measurement at room temperature.
本文展示了通过脉冲注入金属有机化学气相沉积（MOCVD）技术在Al2O3衬底上生长的La1-xSrxMnyO3（LSMO）薄膜的巨磁电阻（CMR）特性结果。所生长的具有不同Sr（0.05≤x≤0.3）和Mn过量（y>1）浓度的薄膜呈现纳米结构，垂直排列的柱状微晶垂直于薄膜平面分布。研究发现，薄膜的微观结构、电阻率和磁阻特性强烈依赖于锶和锰的浓度。所有薄膜（包括低Sr含量的薄膜）在特定温度Tm下都表现出锰氧化物典型的金属-绝缘体转变。对于Mn含量恒定的薄膜，Tm与Sr含量的依赖关系存在最大值，且随着薄膜中Mn过量的增加，该最大值向较低的Sr值移动。此外，薄膜中Mn过量浓度越高，获得的Tm值越高。对于x = 0.17 - 0.18且y = 1.15的纳米结构LSMO薄膜，观察到最高的Tm值（270 K），而对于x = 0.3且y = 1.15的薄膜，在室温（290 K）下实现了最高的低场磁电阻（50 mT时为0.8%）。与文献中报道的未添加额外绝缘氧化物相制备的镧锰氧化物薄膜的结果相比，所获得的低场MR值相对较高。这可能是由于高居里温度（383 K）、室温下的高饱和磁化强度（870 emu/cm3）以及相对较薄的晶界所致。所获得的结果使得能够制造用于室温下低磁场测量的CMR传感器。
