Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, and CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China.
National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, People's Republic of China.
J Am Chem Soc. 2017 Nov 15;139(45):16398-16404. doi: 10.1021/jacs.7b10071. Epub 2017 Nov 1.
Superconductivity is mutually exclusive with ferromagnetism, because the ferromagnetic exchange field is often destructive to superconducting pairing correlation. Well-designed chemical and physical methods have been devoted to realize their coexistence only by structural integrity of inherent superconducting and ferromagnetic ingredients. However, such coexistence in freestanding structure with nonsuperconducting and nonferromagnetic components still remains a great challenge up to now. Here, we demonstrate a molecule-confined engineering in two-dimensional organic-inorganic superlattice using a chemical building-block approach, successfully realizing first freestanding coexistence of superconductivity and ferromagnetism originated from electronic interactions of nonsuperconducting and nonferromagnetic building blocks. We unravel totally different electronic behavior of molecules depending on spatial confinement: flatly lying Co(Cp) molecules in strongly confined SnSe interlayers weaken the coordination field, leading to spin transition to form ferromagnetism; meanwhile, electron transfer from cyclopentadienyls to the Se-Sn-Se lattice induces superconducting state. This entirely new class of coexisting superconductivity and ferromagnetism generates a unique correlated state of Kondo effect between the molecular ferromagnetic layers and inorganic superconducting layers. We anticipate that confined molecular chemistry provides a newly powerful tool to trigger exotic chemical and physical properties in two-dimensional matrixes.
超导性与铁磁性相互排斥，因为铁磁交换场通常会破坏超导配对相关。人们致力于通过固有超导和铁磁成分的结构完整性来实现它们的共存，为此设计了化学和物理方法。然而，在具有非超导和非铁磁成分的自由站立结构中实现这种共存至今仍然是一个巨大的挑战。在这里，我们通过化学结构单元的方法，在二维有机-无机超晶格中进行了分子限域工程，成功地实现了首个源自非超导和非铁磁结构单元电子相互作用的自由站立超导性和铁磁性共存。我们揭示了分子根据空间限域而具有完全不同的电子行为：在强烈受限的 SnSe 夹层中，平躺的 Co(Cp)分子削弱了配位场，导致自旋转变形成铁磁性；同时，来自环戊二烯基的电子转移到 Se-Sn-Se 晶格中诱导了超导状态。这种全新的共存超导性和铁磁性产生了分子铁磁层和无机超导层之间独特的科顿效应关联态。我们预计，受限的分子化学为在二维基质中引发奇异的化学和物理性质提供了一种新的强大工具。
