Abstract
Quantum Griffiths singularity was theoretically proposed to interpret the phenomenon of divergent dynamical exponent in quantum phase transitions. It has been discovered experimentally in three-dimensional (3D) magnetic metal systems and two-dimensional (2D) superconductors. But, whether this state exists in lower dimensional systems remains elusive. Here, we report the signature of quantum Griffiths singularity state in quasi-one-dimensional (1D) Ta2PdS5 nanowires. The superconducting critical field shows a strong anisotropic behavior and a violation of the Pauli limit in a parallel magnetic field configuration. Current-voltage measurements exhibit hysteresis loops and a series of multiple voltage steps in transition to the normal state, indicating a quasi-1D nature of the superconductivity. Surprisingly, the nanowire undergoes a superconductor-metal transition when the magnetic field increases. Upon approaching the zero-temperature quantum critical point, the system uncovers the signature of the quantum Griffiths singularity state arising from enhanced quenched disorders, where the dynamical critical exponent becomes diverging rather than being constant.
Highlights
Quantum Griffiths singularity was theoretically proposed to interpret the phenomenon of divergent dynamical exponent in quantum phase transitions
One example of the quantum phase transition (QPT) has been extensively studied that is the superconductor-insulator transition (SIT) or superconducting-metal transition (SMT), in which a continuous phase transition occurs at the zero-temperature limit as a function of external tuning parameters, such as external electric fields, carrier density, and out-of-plane magnetic fields[1,9]
The latest remarkable observations of the quantum Griffiths singularity in thin Ga films[12], LaAlO3/SrTiO3(110) interface[13], monolayer NbSe214, and ionic liquid gated ZrNCl and MoS215 shed a new light on the understanding of SMT in two-dimensional (2D) system[16]
Summary
Quantum Griffiths singularity was theoretically proposed to interpret the phenomenon of divergent dynamical exponent in quantum phase transitions It has been discovered experimentally in three-dimensional (3D) magnetic metal systems and two-dimensional (2D) superconductors. The latest remarkable observations of the quantum Griffiths singularity in thin Ga films[12], LaAlO3/SrTiO3(110) interface[13], monolayer NbSe214, and ionic liquid gated ZrNCl and MoS215 shed a new light on the understanding of SMT in two-dimensional (2D) system[16] Whether this phenomenon would appear in lower dimensional superconducting systems remains elusive. As the temperature approaches zero, the dynamical critical exponent shows a divergent value, which is a signature of quantum Griffiths singularity state
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