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有两个，也只能有两个不同的值，这通常被称为自旋向上和向下。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处理数字的方式类似，只需要两位数字，电子的两个自旋就可以用来存储信息，可以想象地用来进行计算。产生不同自旋的电子可以使用电子或光学手段。在这项提议中，我们正在与马尔堡大学的一个团队合作，他们已经证明，通过使用两个不同波长的非常短的光脉冲，它们可以导致一个自旋的电子朝着一个方向移动，而另一个自旋的电子则朝着相反的方向移动。这产生了一种被称为纯自旋流的效应，其中没有电子的净运动，但出现了两个自旋态的空间分离。Marburg小组在只由一种半导体组成的薄层中展示了这种效应。然而，为了最大限度地展示效果，并制造出一些原型设备，他们需要一个至少有三个不同区域的设备：一个用于产生自旋电流，一个用于检测向上旋转和一个用于向下旋转。这项建议是关于生产这样一种装置，然后我们将供应给马尔堡。马尔堡要求的装置必须由吸收光谱中蓝/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特定类型的半导体。只有少数几个实验室可以培养这种材料。此外，这些设备需要其他半导体，包括一种(硫化镁)，它只在Heriot-Watt常规生产。因此，这一提议将极少数产生自旋流的基团之一与唯一能够产生他们需要的器件的基团聚集在一起。

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.