Andreev reflection (AR) refers to the electron-hole conversion at the normal metal-superconductor interface. In a three-dimensional metal with a spherical Fermi surface, retro (specular) AR can occur with the sign reversal of all three (a single) components of particle velocity. Here, we predict a novel type of AR with the inversion of two velocity components, dubbed “anomalous Andreev reflection” (AAR), which can be realized in a class of materials with a torus-shaped Fermi surface, such as doped nodal line semimetals. For its toroidal circle perpendicular to the interface, the Fermi torus doubles the AR channels and generates multiple AR processes. In particular, the AAR and retro AR are found to dominate electron transport in the light and heavy doping regimes, respectively. We show that the AAR visibly manifests itself as a ridge structure in the spatially resolved nonlocal conductance, in contrast to the peak structure for the retro AR. Our work opens a new avenue for the AR spectroscopy and offers a clear transport signature of the torus-shaped Fermi surface.

安德列夫反射（AR）表示法向金属-超导体界面的电子-空穴转换。在具有球形费米表面的三维金属中，逆向（镜面）AR会发生，而粒子速度的所有三个（单个）分量的符号都反转。在这里，我们预测了一种新型的AR，它具有两个速度分量的反转，称为“异常安德列夫反射”（AAR），可以在具有圆环形费米表面的一类材料中实现，例如掺杂的节点线半金属。对于垂直于界面的环形圆，费米圆环将AR通道加倍，并生成多个AR进程。特别是，发现AAR和逆向AR分别在轻掺杂和重掺杂体系中支配电子传输。我们显示，AAR在空间分辨的非局部电导中明显表现为脊结构，这与复古AR的峰结构相反。我们的工作为AR光谱学开辟了新途径，并为圆环形的费米表面提供了清晰的传输特征。