Three-dimensional quantum Griffiths singularity in bulk iron-pnictide superconductors

• DOI: 10.48550/arxiv.2406.10193
• Publication Date: 2024-06-25
• Authors: Shao-Bo Liu; Congkuan Tian; Yongqing Cai; Hang Cui; Xinjian Wei; Mantang Chen; Yang Zhao; Yuan Sui; Shuyue Guan; Shuang Jia; Yu Zhang; Ya Feng; Jiankun Li; Jian Cui; Yuanjun Song; Tingting Hao; Chaoyu Chen; Jian-Hao Chen
• Keywords: Superconductivity (cond-mat.supr-con); Condensed Matter - Strongly Correlated Electrons; Strongly Correlated Electrons (cond-mat.str-el); Condensed Matter - Superconductivity; FOS: Physical sciences; 02 engineering and technology; 0210 nano-technology; Research Article

ABSTRACT The quantum Griffiths singularity (QGS) is a phenomenon driven by quenched disorders that break conventional scaling invariance and result in a divergent dynamic critical exponent during quantum phase transitions (QPT). While this phenomenon has been well-documented in low-dimensional conventional superconductors and in three-dimensional (3D) magnetic metal systems, its presence in 3D superconducting systems and in unconventional high-temperature superconductors (high-Tc SCs) remains unclear. In this study, we report the observation of robust QGS in the superconductor-metal transition (SMT) of both quasi-2D and 3D anisotropic unconventional high-Tc superconductor CaFe1-xNixAsF (x <5%) bulk single crystals, where the QGS states persist to up to 5.3 K. A comprehensive quantum phase diagram is established that delineates the 3D anisotropic QGS of SMT induced by perpendicular and parallel magnetic fields. Our findings reveal the universality of QGS in 3D superconducting systems and unconventional high-Tc SCs, thereby substantially expanding the range of applicability of QGS.