我们研究了$A_2$ CoSi $_2$ O $_7$（$A$ =Ca，Sr，Ba）晶体的磁性和介电性能，该晶体由CoO $_4$和SiO $_4$四面体通过角部相互连接而成二维网络.在Ca $_2$ CoSi $_2$ O $_7$中，在5.7 K下发生弱铁磁转变，其中平行于c轴的介电常数显示伴随的异常。在5.7 K以下观察到大的磁电容效应，在5.1 K时$Δ\varepsilon (H)/\varepsilon (0) \equiv [\varepsilon (H)-\varepsilon (0)]/\varepsilon (0)$达到13%.这些结果表明在Ca $_2$ CoSi $_2$ O $_7$中磁性和介电性之间存在强耦合。Sr $_2$ CoSi $_2$ O $_7$表现出与Ca $_2$ CoSi $_2$ O $_7$类似的磁电行为。相反，在Ba $_2$ CoSi $_2$ O $_7$中，其具有与Ca $_2$ CoSi $_2$ O $_7$不同的SiO $_4$和CoO $_4$四面体排列，几乎观察不到磁电容。$A_2$ CoSi $_2$ O $_7$的准二维晶体结构是其磁电容效应的关键。
英文摘要：
We have investigated the magnetic and dielectric properties of $A_2$CoSi$_2$O$_7$ ($A$=Ca, Sr, and Ba) crystals with a two-dimensional network of CoO$_4$ and SiO$_4$ tetrahedra connected with each other through the corners. In Ca$_2$CoSi$_2$O$_7$, a weak ferromagnetic transition occurs at 5.7 K, where the dielectric constant parallel to the c axis shows a concomitant anomaly. The large magnetocapacitance effect is observed below 5.7 K; $Δ\varepsilon (H)/\varepsilon (0) \equiv [\varepsilon (H)-\varepsilon (0)]/\varepsilon (0)$ reaches 13 % at 5.1 K\@. These results indicate a strong coupling between the magnetism and dielectricity in Ca$_2$CoSi$_2$O$_7$. Sr$_2$CoSi$_2$O$_7$ shows a similar magnetoelectric behavior to that of Ca$_2$CoSi$_2$O$_7$. In contrast, in Ba$_2$CoSi$_2$O$_7$, which has the different arrangement of SiO$_4$ and CoO$_4$ tetrahedra from that of Ca$_2$CoSi$_2$O$_7$, the magnetocapacitance is hardly observed. The key for the magnetocapacitance effect of $A_2$CoSi$_2$O$_7$ lies in the quasi-two-dimensional crystal structure.
Magnetic and dielectric investigations of $γ$ - Fe${_2}$WO${_6}$
本文报道了$γ$ - Fe ${_2}$ WO ${_6}$体系的磁性、热力学和介电性质.在中心对称的$Pbcn$空间群中结晶，这种特定的多晶型物表现出许多不同的磁转变，所有这些都被认为表现出有限的磁-介电耦合。在最低的测量温度下，磁基态似乎是玻璃状的，证明了磁弛豫的等待时间的依赖性。也反映在频率相关的介电测量，这些签名可能出现的结果，氧的非化学计量，这促进了不均匀的磁和电子基态。
Suppression of magnetic phase transition at high magnetic field and non-Debye's nature of nano-crystalline Gd$_2$CoMnO$_6$: a detail study of physical properties
Dielectric and multiferroic behavior in a Haldane spin-chain compound Sm2BaNiO5 due to an interplay between crystal-field effect and exchange interaction
