1] Department of Materials, Imperial College London, London SW7 2AZ, UK [2] London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, UK.
1] Department of Materials, Imperial College London, London SW7 2AZ, UK [2] London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, UK [3] Department of Chemistry, Imperial College London, London SW7 2AZ, UK.
Nat Commun. 2014;5:3079. doi: 10.1038/ncomms4079.
The viability of dilute magnetic semiconductors in applications is linked to the strength of the magnetic couplings, and room temperature operation is still elusive in standard inorganic systems. Molecular semiconductors are emerging as an alternative due to their long spin-relaxation times and ease of processing, but, with the notable exception of vanadium-tetracyanoethylene, magnetic transition temperatures remain well below the boiling point of liquid nitrogen. Here we show that thin films and powders of the molecular semiconductor cobalt phthalocyanine exhibit strong antiferromagnetic coupling, with an exchange energy reaching 100 K. This interaction is up to two orders of magnitude larger than in related phthalocyanines and can be obtained on flexible plastic substrates, under conditions compatible with routine organic electronic device fabrication. Ab initio calculations show that coupling is achieved via superexchange between the singly occupied a1g () orbitals. By reaching the key milestone of magnetic coupling above 77 K, these results establish quantum spin chains as a potentially useable feature of molecular films.
稀磁半导体在应用中的可行性与其磁耦合强度有关，而在标准无机体系中，室温操作仍然难以实现。由于分子半导体具有较长的自旋弛豫时间和易于加工的特点，因此它们作为一种替代方案而出现，但除了钒-四氰基乙烯之外，磁性转变温度仍然远低于液氮的沸点。在这里，我们表明，酞菁钴的分子半导体的薄膜和粉末表现出强的反铁磁耦合，其交换能达到 100 K。这种相互作用比相关酞菁的相互作用大两个数量级，并且可以在与常规有机电子器件制造兼容的条件下在柔性塑料衬底上获得。从头算计算表明，通过单占据的 a1g()轨道之间的超交换实现了耦合。通过达到 77 K 以上的磁耦合关键里程碑，这些结果确立了量子自旋链作为分子膜中一种潜在可用的特征。
