Improper ferroelectrics are described by two order parameters: a primary one, driving a transition to long-range distortive, magnetic, or otherwise nonelectric order, and the electric polarization, which is induced by the primary order parameter as a secondary, complementary effect. Using low-temperature scanning probe microscopy, we show that improper ferroelectric domains in ${\mathrm{YMnO}}_3$ can be locally switched by electric field poling. However, subsequent temperature changes restore the as-grown domain structure as determined by the primary lattice distortion. The backswitching is explained by uncompensated bound charges occurring at the newly written domain walls due to the lack of mobile screening charges at low temperature. Thus, the polarization of improper ferroelectrics is in many ways subject to the same electrostatics as in their proper counterparts, yet complemented by additional functionalities arising from the primary order parameter. Tailoring the complex interplay between primary order parameter, polarization, and electrostatics is therefore likely to result in novel functionalities specific to improper ferroelectrics.

中文翻译：

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YMnO3中不适当铁电畴的局部控制

不正确的铁电材料由两个阶次参数来描述：一次阶次，驱动到长程畸变，电磁或其他非阶次阶跃的转变，以及由一次阶次参数引起的极化，作为二次互补效应。使用低温扫描探针显微镜，我们显示不适当的铁电畴${\mathrm{氧化锰}}_3$可以通过电场极化本地切换。但是，随后的温度变化恢复了初生晶格畸变所确定的生长畴结构。反向切换是由于在低温下缺少移动屏蔽电荷而在新写入的畴壁处发生的未补偿束缚电荷而解释的。因此，不正确的铁电体的极化在许多方面都受到与其适当的对等体相同的静电作用，但又由初级参数引起的附加功能得到了补充。因此，调整一次参数，极化和静电之间的复杂相互作用可能会导致特定于不适当地铁电体的新型功能。