Electronic and Magnetic Properties of Free Radical Crystals

理解稳定自由基（FRACs）与奇数电子的强相关效应，原则上可以使我们设计所有的“塑料”电子材料，例如。只含有s和p元素的材料，这将使制造一系列有机半导体、磁铁，甚至金属成为可能。在这种模式的转变中，我们将从化学复杂的分子中构建电子元件，而不是从原子中构建电子元件，这有可能导致分子电子学时代的到来。惰性气体的电子数为偶数，如果缺少一个电子，自由基的化学活性就会很高。尽管如此，化学家们已经发现了使它们稳定的方法：添加芳香环，使未配对电子离域，或引入大块取代基作为侧基。

Understanding the strong correlation effects in stable free radicals (FRACs) with an odd number of electrons could in principle enable us to engineer all ``plastic'' electronic materials, eg. materials containing only s and p elements, which could make it then possible to fabricate a whole range of organic semiconductors, magnets, and maybe even metals. In this paradigm shift, instead of building electronics from atoms, we would be building them from chemically complex molecules, which has the potential to give rise to the age of molecular electronics. Being one electron short of what is required for a filled noble gas configuration, which have an even number of electrons, makes the free radicals chemically highly reactive. Nevertheless, chemists have discovered ways how render them stable: the addition of aromatic rings, delocalization of the unpaired electron, or the introduction of bulky substituents as side-groups. The physical properties of FRACs are governed by strong interactions due to wavefunction overlap between individual molecules. To study these strong interactions, we plan to drastically alter the physical properties of these compounds by two means: tuning the wavefunction overlap by applying pressure, and changing the molecular building block size by altering their side-groups. This will allow us to drive these materials towards a quantum critical point (QCP), at which two ground states close by in energy are competing with each other. This competition leads to the creation of novel quantum phases which then will allow us to study these strong interactions in detail.