Fluctuation-induced continuous transition and quantum criticality in Dirac semimetals

Article

关键词: CRITICAL EXPONENTS;    PHASE-TRANSITIONS;    POTTS-MODEL;    RENORMALIZATION;    FERMIONS;    COLLOQUIUM;    EQUATION;   

DOI  :  10.1103/PhysRevB.96.115132

来源: SCIE

【 摘 要 】

We establish a scenario where fluctuations of new degrees of freedom at a quantum phase transition change the nature of a transition beyond the standard Landau-Ginzburg paradigm. To this end, we study the quantum phase transition of gapless Dirac fermions coupled to a Z(3) symmetric order parameter within a Gross-Neveu-Yukawa model in 2+1 dimensions, appropriate for the Kekule transition in honeycomb lattice materials. For this model, the standard Landau-Ginzburg approach suggests a first-order transition due to the symmetry-allowed cubic terms in the action. At zero temperature, however, quantum fluctuations of the massless Dirac fermions have to be included. We show that they reduce the putative first-order character of the transition and can even render it continuous, depending on the number of Dirac fermions N-f. A nonperturbative functional renormalization group approach is employed to investigate the phase transition for a wide range of fermion numbers and we obtain the critical N-f, where the nature of the transition changes. Furthermore, it is shown that for large N-f the change from the first to second order of the transition as a function of dimension occurs exactly in the physical 2+1 dimensions. We compute the critical exponents and predict sizable corrections to scaling for N-f = 2.

【 授权许可】

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