Specular Andreev reflection and its detection

We propose a universal method to detect the specular Andreev reflection taking simple two dimensional Weyl nodal-line semimetal-superconductor double-junction structure as an example. The quasiclassical quantization conditions are established for energy levels of bound states formed in middle semimetal along closed path. establishment is completely based on intrinsic character specularly reflected hole which has same sign relation its wave vector and group velocity with incident electron. This brings about periodic oscillation conductance length semimetal, lack retro-Andreev having opposite positions peaks period can be precisely predicted by conditions. Our detection irrespective details materials, may promote experimental further researches well applications superconducting electronics.