[Prof. Kim, Jun Sung] Quantum transport evidence of isolated topologic…

Caption: (Left up) Crystal structure and (Left down) optical image of nodal-line semimetal SrAs3. (Right up) The theoretically expected torus-shaped Ferim surface with smoke-ring-type pseudospin texture in general nodal-line semimetal and (Right down) reconstructed torus-shape Fermi surface in SrAs3 from experiment results.

Quantum transport evidence of isolated topological nodal-line fermions 

Anomalous transport responses, dictated by the nontrivial band topology, are the key for application of topological materials to advanced electronics and spintronics. One promising platform is topological nodal-line semimetals due to their rich topology and exotic physical properties. However, their transport signatures have often been masked by the complexity in band crossings or the coexisting topologically trivial states. Here we show that, in slightly hole-doped SrAs3, the single-loop nodal-line states are well-isolated from the trivial states and entirely determine the transport responses. The characteristic torus-shaped Fermi surface and the associated encircling Berry flux of nodal-line fermions are clearly manifested by quantum oscillations of the magnetotransport properties and the quantum interference effect resulting in the two-dimensional behaviors of weak antilocalization. These unique quantum transport signatures make the isolated nodal-line fermions in SrAs3 desirable for novel devices based on their topological charge and spin transport.