Magnetic hybrid-improper ferroelectrics show potential for multiferroicity that is mediated by nonpolar structural distortions that give rise to both ferroelectricity and a net-magnetic spin canting. Here, we report on a pronounced magnetoelectric response of the ferroelectric state to the intrinsic magnetic ordering and to external magnetic fields in $\mathrm{Ca}{}_3{\mathrm{Mn}}_{1.9}{\mathrm{Ti}}_{0.1}\mathrm{O}{}_7$, a layered perovskite-type system. We observe a sixfold increase in the temperature-dependent response of the polarization-induced optical second-harmonic-generation (SHG) signal to the magnetic order that we explain as a magnetically triggered interlayer coupling of the polar order. Furthermore, an applied magnetic field up to 3 T along the direction of the net magnetization enhances the polarization-induced SHG signal by about 30%. We interpret this as magnetic-field-induced spin canting, which possibly affects the Mn-O bonds and hence the polarization. Optical SHG is of particular advantage to this study as it provides access to the electric polarization with spatial resolution of its domains, unobstructed by the leakage currents that impede contact-based measurements. Our investigations advance the understanding and potential of a highly promising new category of multiferroic materials for magnetoelectric cross control and functionalization.

中文翻译：

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多铁杂化非准铁电Ca3Mn1.9Ti0.1O7中的磁电耦合

磁杂化非适当铁电体表现出多铁性的潜力，这种多铁性是由非极性结构畸变介导的，这种畸变会产生铁电性和净磁自旋倾斜。在这里，我们报告了铁电态对固有磁序和外部磁场的明显磁电响应$钙{}_3{锰}_{1.9}{钛}_{0.1}\mathrm{氧}{}_7$，一种层状钙钛矿型系统。我们观察到偏振引起的光学二次谐波产生（SHG）信号对磁阶的温度依赖性响应增加了六倍，我们将其解释为磁触发的极阶层间耦合。此外，沿净磁化强度方向施加高达 3 T 的磁场可将极化引起的 SHG 信号增强约 30%。我们将此解释为磁场引起的自旋倾斜，这可能会影响 Mn-O 键，从而影响极化。光学倍频在这项研究中具有特别的优势，因为它提供了具有域空间分辨率的电极化途径，不受阻碍基于接触的测量的泄漏电流的阻碍。我们的研究增进了对用于磁电交叉控制和功能化的极具前景的新型多铁性材料的理解和潜力。