中国物理B ›› 2024, Vol. 33 ›› Issue (2): 27401-027401.doi: 10.1088/1674-1056/ad03dc
Wei-Tao Lyu(吕伟涛)1, Qiang Zhi(支强)1, Jie Hu(胡洁)2, Jing Li(李婧)1, and Sheng-Cai Shi(史生才)1,†
Wei-Tao Lyu(吕伟涛)1, Qiang Zhi(支强)1, Jie Hu(胡洁)2, Jing Li(李婧)1, and Sheng-Cai Shi(史生才)1,†
摘要: Disordered superconducting materials like NbTiN possess a high kinetic inductance fraction and an adjustable critical temperature, making them a good choice for low-temperature detectors. Their energy gap ($\varDelta$), critical temperature ($T_{\rm c}$), and quasiparticle density of states (QDOS) distribution, however, deviate from the classical BCS theory due to the disorder effects. The Usadel equation, which takes account of elastic scattering, non-elastic scattering, and electro-phonon coupling, can be applied to explain and describe these deviations. This paper presents numerical simulations of the disorder effects based on the Usadel equation to investigate their effects on the $\varDelta $, $T_{\rm c}$, QDOS distribution, and complex conductivity of the NbTiN film. Furthermore, NbTiN superconducting resonators with coplanar waveguide (CPW) structures are fabricated and characterized at different temperatures to validate our numerical simulations. The pair-breaking parameter $\alpha $ and the critical temperature in the pure state $T_{\rm c}^{\rm P}$ of our NbTiN film are determined from the experimental results and numerical simulations. This study has significant implications for the development of low-temperature detectors made of disordered superconducting materials.
中图分类号: (Effects of disorder)