Development of Semiconductor structures for Spin current detection

电子具有一种称为自旋的量子力学性质。一个电子的自旋可以取两个，而且只有两个，不同的值，这通常被称为自旋向上和自旋向下。多年来，已经有可能产生和探测具有不同自旋的电子，近年来这导致了自旋电子学领域的发展。在自旋电子学中，人们设想电子的自旋可以用来传递信息。与计算机以二进制形式存储和操作数字的方式类似，只需要两个数字，电子的两个自旋可以用来存储信息，并且可以想象用于执行计算。产生具有不同自旋的电子可以用电学或光学方法来完成。在这个提案中，我们正在与马尔堡大学的一个小组合作，他们已经证明，通过使用两种不同波长的非常短的光脉冲，它们可以使具有一个自旋的电子向一个方向移动，而具有另一个自旋的电子则向相反方向移动。这产生了一种被称为纯自旋电流的效应，在这种情况下，没有电子的净运动，但两个自旋状态的空间分离发生了。马尔堡小组已经在仅由一种半导体制成的薄层上证明了这种效应。然而，为了最好地展示这种效果，并制造出一些原型装置，他们需要一个至少有三个不同区域的装置：一个产生自旋电流，一个检测向上自旋，一个检测向下自旋。这个建议是关于生产这样一个设备，然后我们将提供给马尔堡。马尔堡要求的器件必须由能够吸收光谱蓝色/绿色区域的光的材料制成，这意味着只能使用基于化合物硒化锌的某种类型的半导体。只有少数实验室能种植这种材料。此外，这些设备还需要其他半导体，包括一种仅在赫瑞瓦特常规制造的半导体（硫化镁）。因此，这一提议将极少数能够产生自旋电流的小组之一与唯一能够生产他们所需设备的小组聚集在一起。

An electron possesses a quantum mechanical property known as spin. The spin of an electron can take two, and only two, different values, which are often referred to as spin up and spin down . For many years is has been possible to generate and detect electrons with different spins, and in recent years this has lead to the development of the field of spintronics. In spintronics, it is envisaged that the spin of an electron can be used to convey information. By analogy with the way computers store and manipulate numbers in binary form, needing only two digits, the two spins of an electron could be used to store information and conceivably used to perform calculations.The creation of electrons with different spins can be done using electrical or optical means. In this proposal, we are working with a group at Marburg University who have demonstrated that by using very short pulses of light at two different wavelengths, they can cause electrons with one spin to move in one direction, while those with the other spin move in the opposite direction. This produces an effect known as a pure spin current, where there is no net movement of electrons, but a spatial separation of the two spin states occurs.The Marburg group have demonstrated this effect in a thin layer made of only one kind of semiconductor. However to show the effect to best advantage, and produce some prototype devices, they need a device with at least three distinct regions: one to generate the spin currents, one to detect the up spins and one for the down spins. This proposal is concerned with producing such a device which we will then supply to Marburg.The devices which Marburg require, must be made from materials which absorb light in the blue/green regions of the spectrum, and this means that only a certain type of semiconductor, based on the compound zinc selenide, can be used. There are only a few laboratories which can grow this material. In addition, the devices require other semiconductors including one (magnesium sulphide) which is only routinely made at Heriot-Watt. This proposal therefore brings together one of the very few groups to have produced spin currents with the only group capable of producing the devices which they need.