Single-molecule photo-spintronics

自旋电子学与电子学类似，除了它利用电子的自旋（一种与角动量相似的量子力学性质，与磁性密切相关）和电子的电荷。例如，同时使用自旋和电荷可以使计算机消耗更少的能量。光自旋电子学将光加入其中。这是非常有用的，因为光可以很容易地远距离传递信息（想想光纤）。光和自旋也是量子计算和量子信息等未来量子技术的关键。我们的研究是寻找在光自旋电子学中使用基于碳原子链和环的有机分子的方法。这是一个令人兴奋的前景，因为碳的原子序数低，减少了失去自旋信息的机会，因为有这么多不同的有机分子和连接它们的方法，发现新的和有用的现象的机会实际上是无穷无尽的。我们的计划是研究连接半导体和磁性金属的单分子。单分子实验是困难的，但不是不可能的，我们已经成功地在过去使用改进的扫描隧道显微镜。单分子研究对理解分子电子学有很大帮助，因为单独研究分子可以揭示在大群体中测量时丢失的信息。我们的研究将是光自旋电子学的第一个单分子研究。我们将在半导体中创造一群被激发的电子，通过照亮它，并利用光的偏振来控制电子的自旋。然后我们将测量半导体和铁磁性金属之间的电流。如果电流取决于光的偏振和金属被磁化的方向，这将是自旋通过分子传递的证据。一旦我们证明我们可以通过单个分子进行光自旋电子测量，我们将研究自旋输运如何依赖于半导体、金属、两者之间的电压（称为偏置）以及分子、半导体和金属之间的化学键的类型。这将向我们展示如何在未来的自旋电子和光自旋电子器件中最好地使用有机分子。

Spintronics is like electronics except that it uses the spin of the electron (a quantum mechanical property that behaves like angular momentum and is closely linked to magnetism) as well as the electron's electric charge. Using spin and charge together could lead to computers that use much less energy, for example. Photo-spintronics adds light to the mix. This is very useful because light can easily carry information over long distances (think of optic fibres). Light and spin are also key to future quantum technologies such as quantum computing and quantum information.Our research is to find ways of using organic molecules, based on chains and rings of carbon atoms, in photo-spintronics. This is an exciting prospect because carbon has a low atomic number which reduces the chances of losing spin information, and because there are so many different organic molecules and ways of linking them that the opportunities to find new and useful phenomena are practically endless. Our plan is to study single molecules linking a semiconductor and a magnetic metal. Single molecule experiments are difficult but not impossible, and we have made them successfully in the past using a modified scanning tunnelling microscope. Single molecule studies have helped greatly in understanding molecular electronics because studying molecules individually reveals information that is lost when they are measured in a large group. Ours will be the first single molecule studies in photo-spintronics. We will create a population of excited electrons in the semiconductor by illuminating it and use the polarization of the light to control the spin of the electrons. We will then measure the current between the semiconductor and the ferromagnetic metal. If the current depends on the polarization of the light and the direction in which the metal is magnetized, that will be evidence that spin is being transported through the molecules. Once we show that we can make photo-spintronic measurements through a single molecule, we will investigate how the spin transport depends on the type of semiconductor, the metal, the voltage between the two (known as the bias), and the types of chemical bond between the molecule and the semiconductor and metal. This will show us how best to use organic molecules in future spintronic and photo-spintronic devices.