Speaker
Description
Quantum interference of electrons in disordered conductors is a
sensitive probe of the internal structure of quasiparticles, revealing
universal signatures of symmetry through weak localization (WL) and weak
antilocalization (WAL). While these phenomena are well understood for
conventional Schrödinger and Dirac-Weyl fermions, their fate in the
broader class of multifold chiral fermions remains largely unexplored.
We develop a unified framework for semiclassical transport and quantum
interference in three-dimensional disordered fermions with an arbitrary
pseudospin 𝑠. Starting with a general short-range matrix disorder ℳ, we
derive compact expressions for elastic lifetimes and ladder vertex
corrections for arbitrary pseudospin with multiband effects. We then
show that, in the scalar-disorder limit, while the Drude conductivity is
strongly pseudospin and helicity dependent, the leading
quantum-interference correction exhibits a striking universality: its
magnitude remains identical to that of conventional diffusive metals and
Weyl fermions, while its sign is determined solely by the parity of 2𝑠,
placing half-integer pseudospins in the symplectic class (WAL) and
integer pseudospins in the orthogonal class (WL). We also analyze the
role of interband and intervalley scattering for 𝑠=3/2. By solving the
resulting coupled Bethe-Salpeter equations, we demonstrate that channel
mixing suppresses WAL and drives a crossover toward localization. Our
results establish a general theory of localization across the full
pseudospin hierarchy, revealing the interplay between internal geometry,
symmetry class, and transport universality.