Superconductivity near the (2+1)-Dimensional Ferromagnetic Quantum Critical Point
Yunchao Hao1†, Gaopei Pan2,3†, Kai Sun4*, Zi Yang Meng5*, and Yang Qi1,6*
1State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China 2Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China 3School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China 4Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA 5Department of Physics and HKU-UCAS Joint Institute of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China 6Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
Abstract：We utilize both analytical and numerical methods to study the superconducting transition temperature $T_{\rm c}$ near a fermionic quantum critical point (QCP) using a model constructed by Xu et al. [Phys. Rev. X7, 031059 (2017)] 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 $T_{\rm c}$. We further argue that the $T_{\rm c}$ computed from the BCS theory approximates a pseudogap temperature $T_{\rm PG}$, instead of the Berezinskii–Kosterlitz–Thouless transition temperature $T_{\rm KT}$, which is confirmed by our determinant quantum Monte Carlo simulation. Moreover, due to the fact that electron density of state starts to deplete at $T_{\rm PG}$, the critical scaling of the underlying QCP is also affected below $T_{\rm PG}$. Thus, when studying the critical behavior of fermionic QCPs, we need to monitor that the temperature is above $T_{\rm PG}$ instead of $T_{\rm KT}$. This was often ignored in previous studies.
. [J]. 中国物理快报, 2022, 39(9): 97102-.
Yunchao Hao, Gaopei Pan, Kai Sun, Zi Yang Meng, and Yang Qi. Superconductivity near the (2+1)-Dimensional Ferromagnetic Quantum Critical Point. Chin. Phys. Lett., 2022, 39(9): 97102-.
2022, Vol. 39 
