Polarization switching in lead-free (K_0.40Na_0.60)NbO₃ (KNN) single crystals was studied by switching spectroscopy piezoresponse force microscopy (SS-PFM). Acquisition of multiple hysteresis loops on a closely spaced square grid enables polarization switching parameters to be mapped in real space. Piezoresponse amplitude and phase hysteresis loops show collective symmetric/asymmetric characteristics, affording information regarding the switching behavior of different domains. As such, the out-of-plane polarization states of the domains, including amplitudes and phases can be determined. Our results could contribute to a further understanding of the relationships between polarization switching and polarization vectors at the nanoscale, and provide a feasible method to correlate the polarization hysteresis loops in a domain under an electric field with the polarization vector states.

中文翻译：

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（K，Na）NbO 3无铅压电晶体中极化态的测定

无铅（K _0.40 Na _0.60）NbO _3中的极化转换（KNN）单晶通过开关光谱压电响应力显微镜（SS-PFM）研究。在紧密间隔的正方形网格上采集多个磁滞回线，可以将偏振切换参数映射到实际空间中。压电响应振幅和相位磁滞回线显示出集体对称/非对称特性，提供了有关不同域的开关行为的信息。这样，可以确定域的平面外极化状态，包括振幅和相位。我们的结果可能有助于进一步了解纳米级偏振转换和偏振矢量之间的关系，并提供一种可行的方法来将电场下的磁畴中的磁滞回线与偏振矢量状态相关联。