YMnO_3薄膜的铁电行为及其纳米尺度铁电畴的研究

六方YMnO_3是一种特殊的多铁性材料,因其具有介电常数低、单一极化轴、无挥发性元素等特点,在磁电领域具有独特的优势,但目前关于YMnO_3薄膜的铁电性特别是畴结构的研究相对较少.本文采用溶胶-凝胶法在Si(100)基片上制备了多铁性YMnO_3薄膜,利用掠入射X-射线衍射、原子力显微镜对薄膜的结构及表面形貌进行了分析,用压力显微镜(PFM)技术研究了纳米尺度畴结构及微区电滞行为,并通过I-V,P-E曲线进一步研究了薄膜的漏电流和宏观电滞行为.结果表明,该薄膜为六方钙钛矿结构,YMnO_3晶粒大小均匀并且结晶性较好,薄膜表面粗糙度为7.209 nm.PFM图显示出清晰的电畴结构,结合典型的微区振幅蝴蝶曲线和相位电滞回线,证实该YMnO_3薄膜具有较好的铁电性.由于受内建电场的作用,振幅曲线和相位曲线都向正向偏移,表现出非对称特征.该薄膜的漏电流密度低于10~(-6)A·cm~(-2),因而其电滞回线基本能够达到饱和.

Study on ferroelectric behaviors and ferroelectric nanodomains of YMnO3 thin film

Hexagonal YMnO₃ is a special kind of multiferroics which shows unique advantages in magneto-electric field due to its low permittivity and only c-axis polarization. However, its ferroelectric properties, especially domain structures, have not been intensively investigated. In this study, YMnO₃ film about 270 nm in thickness is prepared on Si(100) substrate by sol-gel spin coating. Structure and morphology of the film are characterized by grazing incidence X-ray diffraction and atomic force microscopy. Domain structure and its reversal behavior on a nanoscale are examined by piezoresponse force microscopy (PFM). The leakage current and ferroelectric property are also investigated. The results show that the film displays a hexagonal perovskite structure with good crystallinity and has smooth surface with a root-mean-square roughness of 7.209 nm. PFM images and typical local piezoresponse loops reveal the good piezoelectric and ferroelectric properties of the YMnO₃ film at room temperature. Meanwhile, the offsets of amplitude loop and phase loop are observed due to the internal electric field. Leakage current density of YMnO₃ film is lower than 10^-6 A·cm^-2, so saturated hysteresis loop can be obtained.
Keywords：3')" href="#">YMnO₃ferroelectricitypiezoresponse force microscopy