Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Phys Rev Lett. 2009 Oct 16;103(16):167003. doi: 10.1103/PhysRevLett.103.167003.
We report the investigation of electron transport through a four-terminal graphene-superconductor hybrid system. Because of the quantum interference of the reflected holes from two graphene-superconductor interfaces with a phase difference theta, it is found that the specular Andreev reflection vanishes at theta=0 while the Andreev retroreflection disappears at theta=pi. This means that retroreflection and specular reflection can be easily controlled and separated in this device. In addition, because of the diffraction effect in the narrow graphene nanoribbon, the reflected hole can exit from both graphene terminals. As the width of nanoribbon increases, the diffraction effect gradually disappears and the reflected hole eventually exits from a particular graphene terminal depending on the type of Andreev reflection.
我们报告了通过四端石墨烯-超导混合系统的电子输运研究。由于两个石墨烯-超导界面处反射空穴的量子干涉具有相位差θ，因此发现在θ=0 时镜面安德烈夫反射消失，而在θ=π 时安德烈夫背反射消失。这意味着在该器件中可以很容易地控制和分离背反射和镜面反射。此外，由于在窄石墨烯纳米带中的衍射效应，反射空穴可以从两个石墨烯端退出。随着纳米带宽度的增加，衍射效应逐渐消失，并且根据安德烈夫反射的类型，反射空穴最终从特定的石墨烯端退出。
