Superconductivity near the (2+1)-Dimensional Ferromagnetic Quantum Critical Point

Abstract

In this work, we utilize both analytical and numerical methods to study the superconducting transition temperature T c near a fermionic quantum critical point (QCP) using a model constructed in Ref. [1] as an example. In this model, the bosonic critical fluctuation plays the role of pairing glue for the Cooper pairs, and we use a Bardeen-Cooper-Schrieffer-type mean-field theory to estimate T c . We further argue that the T c computed from the BCS theory approximates a pseudogap temperature T PG, instead of the Berenzinskii-Kosterlitz-Thouless-transition temperature T KT, which is confirmed by our determinant quantum Monte Carlo (DQMC) simulation. Moreover, due to the fact that electron density of state starts to deplete at T PG, the critical scaling of the underlying QCP is also affected below T PG. Thus, when studying the critical behavior of fermonic QCPs, we need to monitor that the temperature is above T PG instead of T KT. This was often ignored in previous studies.