Quantum Griffiths singularity in three-dimensional MoTiN superconducting films
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2024
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| author | Wang, Zi-Xiao Jing, Tian-Yu Han, Zi-Yan Gao, Kuang-Hong Li, Song-Ci Li, Zhi-Qing |
| author_facet | Wang, Zi-Xiao Jing, Tian-Yu Han, Zi-Yan Gao, Kuang-Hong Li, Song-Ci Li, Zhi-Qing |
| contents | Quantum Griffiths singularity (QGS) has been experimentally observed in a range of two-dimensional (2D) superconducting systems. Although it is theoretically suggested that the QGS also exists in three-dimensional (3D) superconductors, there is almost no experimental support to the theoretical prediction. In the present paper, we observe the occurrence of QGS in a series of $\sim$80-nm-thick Mo$_{0.8}$Ti$_{0.2}$N$_x$ ($0.84 \lesssim x \lesssim 1.12$) superconducting films near the field-driven superconductor-metal transition (SMT). These films have a NaCl structure and are 3D with respect to the superconductivity. For each film, the low-temperature magnetoresistance isotherms, measured at magnetic fields being perpendicular or parallel to the film plane, do not cross at a single point but at a clear wide region. The dynamical critical exponents $zν_{\perp}$ (for perpendicular field) and $zν_{\parallel}$ (for parallel field) obtained by analyzing the related magnetoresistance isotherms increase with decreasing temperature and tend to diverge as $T\rightarrow 0$ K. In addition, the effective resistivity data for the perpendicular and parallel field in the vicinity of the SMTs both obey an activated scaling based on the random transverse-field Ising model. We also fabricate a $\sim$80-nm-thick (Mo$_{0.8}$Ti$_{0.2}$)$_2$N$_{1.06}$ superconducting film with face-centered cubic structure at low nitrogen partial pressure. It is found that the low-temperature magnetoresistance isotherms for the perpendicular (parallel) field cross at a single point and the resistivity data for the perpendicular (parallel) field in the vicinity of the field-induced SMT obey the power-law scaling deduced from the dirty-boson model. Our results provide unambigous experimental evidence for the existence of QGS in 3D superconductors. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2402_01347 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Quantum Griffiths singularity in three-dimensional MoTiN superconducting films Wang, Zi-Xiao Jing, Tian-Yu Han, Zi-Yan Gao, Kuang-Hong Li, Song-Ci Li, Zhi-Qing Superconductivity Disordered Systems and Neural Networks Quantum Griffiths singularity (QGS) has been experimentally observed in a range of two-dimensional (2D) superconducting systems. Although it is theoretically suggested that the QGS also exists in three-dimensional (3D) superconductors, there is almost no experimental support to the theoretical prediction. In the present paper, we observe the occurrence of QGS in a series of $\sim$80-nm-thick Mo$_{0.8}$Ti$_{0.2}$N$_x$ ($0.84 \lesssim x \lesssim 1.12$) superconducting films near the field-driven superconductor-metal transition (SMT). These films have a NaCl structure and are 3D with respect to the superconductivity. For each film, the low-temperature magnetoresistance isotherms, measured at magnetic fields being perpendicular or parallel to the film plane, do not cross at a single point but at a clear wide region. The dynamical critical exponents $zν_{\perp}$ (for perpendicular field) and $zν_{\parallel}$ (for parallel field) obtained by analyzing the related magnetoresistance isotherms increase with decreasing temperature and tend to diverge as $T\rightarrow 0$ K. In addition, the effective resistivity data for the perpendicular and parallel field in the vicinity of the SMTs both obey an activated scaling based on the random transverse-field Ising model. We also fabricate a $\sim$80-nm-thick (Mo$_{0.8}$Ti$_{0.2}$)$_2$N$_{1.06}$ superconducting film with face-centered cubic structure at low nitrogen partial pressure. It is found that the low-temperature magnetoresistance isotherms for the perpendicular (parallel) field cross at a single point and the resistivity data for the perpendicular (parallel) field in the vicinity of the field-induced SMT obey the power-law scaling deduced from the dirty-boson model. Our results provide unambigous experimental evidence for the existence of QGS in 3D superconductors. |
| title | Quantum Griffiths singularity in three-dimensional MoTiN superconducting films |
| topic | Superconductivity Disordered Systems and Neural Networks |
| url | https://arxiv.org/abs/2402.01347 |