石墨炔铁磁性材料的制备、磁性和输运性质研究

Recently, graphdiyne (GDY) has been regarded as one of the most promising novel carbon-based semiconductor materials due to its direct bandgap, high mobility compared favourably with graphene and low cost. Especially the magnetic property of GDY has also attracted broad attention because of the weak spin-orbital coupling and fairly long spin relaxation length, which makes it suitable for the application in new-type information storage and spintronic devices. However, the absence of intrinsic ferromagnetic ordering in perfect graphdiyne hinders its development in related devices. This project devotes to prepare doped or substituted graphdiyne-based material with different elements from the perspective of doping vario-property. By inducing interaction between carbon atom and exotic atom, we can expect to realize long-range ferromagnetic order by means of introducing significant local magnetic moment as well as improving charge transfer, and then clarify the micro-adjusting mechanism on magnetic properties with different types and doping ratios of exotic atom. On this basis, combined with the measurement of electrical transport properties, we will investigate the transport properties of graphdiyne-based material under magnetic field and further reveal the influence rule of changed magnetic order on its physical properties such as magnetic resistance. The implementation of this project will provide beneficial theory and experiment basis for fabricating two-dimensional carbon-based materials with the coexistence of magnetic order and semiconductivity.

石墨炔由于具有直接带隙，媲美石墨烯的高迁移率、制备成本低廉等特性，被视为未来最具发展潜力的新型碳素半导体材料之一。特别是石墨炔的磁性也引起了人们广泛的关注，因其具有弱的自旋轨道耦合及长的自旋弛豫长度，非常适合在新型信息存储及自旋电子器件中应用。然而，完美石墨炔材料中缺乏本征铁磁序，成为制约其在自旋相关器件中应用的关键问题。本项目从石墨炔掺杂改性的角度出发，制备不同异元素掺杂或取代的石墨炔基材料，通过异原子与碳原子的丰富相互作用引入局域磁矩，改善电荷转移特性，从而实现长程铁磁序，并在此过程中阐明不同元素掺杂种类及比例对材料磁性特征的调节机制。在此基础上，结合电输运性质的测量，研究石墨炔基磁性材料在磁场作用下的电荷输运特性，揭示磁有序的改变对磁阻等物理特性的影响规律。本项目的实施可以为二维碳基材料中磁有序及半导体特性的共存提供有益的理论与实验基础。

信息技术的飞速发展使得摩尔定律面临巨大的挑战。如何在半导体材料中集成铁磁序已成为材料科学领域的研究热点，因为这为信息处理器件等涉及自旋的新型功能器件的制备提供了有效的途径。特别是以石墨炔半导体为代表的碳基材料，由于具有特殊的结构和电子特性，被认为是有潜力的功能材料。此类材料中所表现出的弱自旋轨道耦合作用和较长的自旋扩散长度，赋予其在自旋电子学器件中的巨大应用前景。基于此，本项目主要从化学修饰的石墨炔制备与合成出发，系统研究了不同异元素对石墨炔本征磁特性和半导体性能的影响，发现了以硫掺杂石墨炔、Fe-N共掺石墨炔、氟取代石墨炔等几种不同类型的碳基铁磁半导体材料。其中，硫掺杂石墨炔表现出室温以上的铁磁序，实现了室温下0.047emu/g的剩余磁化强度和高达460K的铁磁转变温度，表明其在磁存储领域的应用潜力巨大；采用Fe-N共掺策略修饰的石墨炔在实现205K的居里温度的同时还展现了215cm2·V-1·s-1的迁移率，作为一种高导电性的铁磁半导体材料有望应用于印刷电子器件；利用自下而上的合成策略制备的氟取代石墨炔膜，除了铁磁序与半导体性共存以外，还实现了320cm2·V-1·s-1的迁移率，有助于探索石墨炔基自旋电子器件。结合理论计算，对相关材料体系中的磁有序起源进行了深入分析，揭示了元素种类、掺杂比例对石墨炔材料磁特性的调控规律。本项目的实施不仅有助于深入理解石墨炔基碳材料的本征物性及其调控规律，还对未来相关碳基电子器件的发展提供了有益的指导与助力。