Nature of the magnetic phase transition in a Weyl semimetal

作者：Lee Yu Li; Lee Yu Wen

来源：PHYSICAL REVIEW B, 2017, 96(4): 045115.

DOI：10.1103/PhysRevB.96.045115

We investigate the nature of the magnetic phase transition induced by the short-ranged electron-electron interactions in a Weyl semimetal by using the perturbative renormalization-group method. We find that the critical point associated with the quantum phase transition is characterized by a Gaussian fixed point perturbed by a dangerously irrelevant operator. Although the low-energy and long-distance physics is governed by a free theory, the velocities of the fermionic quasiparticles and the magnetic fluctuations suffer from nontrivial renormalization effects. In particular, their ratio approaches one at low energies, which indicates an emergent Lorentz symmetry at the quantum critical point. We further investigate the stability of the fixed point in the presence of weak disorder preserving the chiral symmetry. We show that while the fixed point is generally stable against weak disorder, a moderately strong random chemical potential and/or random vector potentialmay induce a quantum phase transition towards a disorder-dominated phase. We propose a global phase diagram of theWeyl semimetal in the presence of both electron-electron interactions and disorder based on our results.

• 出版日期2017-7-14