Mg掺杂Ga0.6Fe1.4O3薄膜的制备及其多铁性能表征

Preparation and Multiferroic Properties of Mg Doped Ga0.6Fe1.4O3 Thin Films

GaFeO3(GFO)是一种同时具有室温铁电和低温亚铁磁性的单相多铁材料,且其磁性转变温度可以通过调节Fe元素含量提高至室温,具有广阔的应用前景.研究发现,室温下Ga0.6Fe1.4O3薄膜具有铁电性和弱磁性,但是由于薄膜的漏电流较大,制约了其实际应用.采用溶胶-凝胶法结合旋涂工艺成功制备了Mg掺杂的Ga0.6Fe1.4O3薄膜,薄膜厚度约为100nm,并对Ga0.6MgxFe1.4-xO3(GMFO)薄膜的铁电性尤其是漏电性能进行了表征.研究结果表明:Mg离子掺杂的薄膜样品在室温下表现出铁电性,当x=0.05时,薄膜具有相对而言优良的铁电性能,矫顽电场强度(Ec)为25kV/cm,剩余极化强度(Pr)为4.89μC/cm^2;适量Mg离子的掺杂可以使薄膜的漏电流密度降低2个数量级,x=0.05时,对应薄膜的漏电流最小,漏电流密度在10-1~10-5A/cm2范围内.随着Mg离子掺杂含量的继续增加,薄膜的漏电流密度逐渐变大.压电力显微技术(PFM)测试结果表明,GMFO薄膜的力电耦合主要来自于薄膜的线性压电信号.GMFO薄膜具有室温弱磁性,当x=0.05时,薄膜具有最大的剩余磁化强度为9.8emu/cm3.该实验结果对于提高GFO多铁材料的性能,从而实现纳米器件的应用具有重要的指导意义.

GaFeO3 (GFO) is a single-phase multiferroic material with ferroelectric properties at room temperature and ferrimagnetism properties at low temperature, and the magnetic transition temperature can be modulated to room temperature by changing the Fe element content. GFO has broad application prospects. It is found that Ga0.6Fe1.4O3 film has ferroelectricity and weak magnetic properties at room temperature, but the leakage current of the film is large, which restricts its practical application. In this paper, Mg doped Ga0.6Fe1.4O3 thin films are successfully prepared by sol-gel combined with spin coating process, and the ferroelectricity, especially the leakage performance of Ga0.6MgxFe1.4-xO3 films are characterized. The results show that the Mg doped film samples exhibit ferroelectricity at room temperature. When x =0.05, the film has relatively good ferroelectricity with a coercive electrical field strength ( E c ) of 25 kV/cm, and residual polarization (Pr) of 4.89 μC/cm^2 . Doping Mg ions in GFO with appropriate amount can reduce the leakage current density by two orders of magnitude. The film with 5% molar ratio Mg doping has the smallest leakage current and the corresponding leakage current densities is in the range of 10 -1 ~10 -5 A/cm^2 . The leakage current of the films increase with the increased content of Mg doping. The piezoresponse force microscopy test show that the electromechanical coupling of the GMFO film is mainly derived from the linear piezoelectric signal. GMFO films have weak magnetic properties at room temperature, and the film has the largest residual magnetization of 9.8 emu/cm 3 as x =0.05. These results can provide guiding for improving the performance of GFO multiferroic materials and promoting the practical application of nanodevice.