Anisotropic Magnetoelectric Coupling and Cotton–Mouton Effects in the Organic Magnetic Charge-Transfer Complex Pyrene–F₄TCNQ

Magnetoelectric coupling is of high current interest because of its potential applications in multiferroic memory devices. Although magnetoelectric coupling has been widely investigated in inorganic materials, such observations in organic materials are extremely rare. Here, we report our discovery that organic charge-transfer (CT) complex pyrene-2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (pyrene–F4TCNQ) can display anisotropic magnetoelectric coupling. Investigation of the crystal structure of pyrene–F4TCNQ complex demonstrates that the magnetoelectric coupling coefficient along the π–π interaction direction is much larger than the value along other directions. Furthermore, magnetoelectric coupling and magnetization can be tuned by changing the fluorine content in complexes. Besides, the Cotton–Mouton effect in pyrene–F4TCNQ is observed, enabling the control of optomagnetic devices. These results can pave the way for a new method for the future development of organic CT complexes and their applications in perpendicular memory devices and energy-transfer-related multiferroics.磁电耦合因在多铁存储器件中的潜在应用前景而备受关注。尽管无机材料中的磁电耦合现象已得到广泛研究，但有机材料中的此类观测却极为罕见。本文报道了我们的新发现：有机电荷转移（CT）复合物芘-2,3,5,6-四氟-7,7,8,8-四氰基对苯二醌二甲烷（pyrene–F4TCNQ）可呈现各向异性磁电耦合特性。对该复合物晶体结构的分析表明，沿π-π相互作用方向的磁电耦合系数远高于其他方向的系数。进一步研究发现，可通过调控复合物中的氟含量来改变其磁电耦合性能与磁化强度。此外，我们还在pyrene–F4TCNQ中观测到了科顿-穆顿效应，这一特性可用于光磁器件的调控。上述研究成果为有机CT复合物的后续开发提供了全新思路，也为其在垂直存储器件及能量转移型多铁材料中的应用铺平了道路。