Quantum phase transitions in two-dimensional superconductors: a review on recent experimental progress

Abstract

Superconductor-insulator/metal transition (SIT/SMT) as a paradigm of quantum phase transition has been a research highlight over the last three decades. Benefit from recent developments in the fabrication and measurements of 2D superconducting films and nanodevices, unprecedented quantum phenomena have been revealed in the quantum phase transitions of 2D superconductors. In this review, we introduce the recent progress on quantum phase transitions in 2D superconductors, focusing on the quantum Griffiths singularity (QGS) and anomalous metal state. Characterized by a divergent critical exponent when approaching zero temperature, QGS of SMT is discovered in ultrathin crystalline Ga films and subsequently detected in various 2D superconductors. The universality of QGS indicates the profound influence of quenched disorder on quantum phase transitions. Besides, in a 2D superconducting system, whether a metallic ground state can exist is a long-sought mystery. Recently, the charge-2e quantum oscillations are observed in nanopatterned superconducting films, indicating the bosonic nature of the anomalous metal state and ending the debate on whether bosons can exist as a metal. The evidences of the anomalous metal states have also been reported in crystalline epitaxial thin films and exfoliated nanoflakes, as well as granular composite films. High quality filters are used in these works to exclude the influence of external high frequency noises in ultralow temperature measurements. The observations of QGS and metallic ground states in 2D superconductors not only reveal the prominent role of quantum fluctuations and dissipations but also provide new perspective to explore quantum phase transitions in superconducting systems.

References in corpus (123)

• Magic-angle graphene superlattices: a new platform for unconventional superconductivity
• "Deconfined" quantum critical points
• Quantum Criticality in Heavy Fermion Metals
• Continuous Quantum Phase Transitions
• Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3
• Quantum phase transitions
• The break up of heavy electrons at a quantum critical point
• Quantum criticality
• Heavy Fermions and Quantum Phase Transitions
• Highly crystalline 2D superconductors
• Evidence for deconfined quantum criticality in a two-dimensional Heisenberg model with four-spin interactions
• Quantum Phase Transitions and Vortex Dynamics in Superconducting Networks
• Visualizing pair formation on the atomic scale in the high-Tc superconductor Bi2Sr2CaCu2O8+d
• Intrinsic Decoherence in Mesoscopic Systems
• Quantum critical point lying beneath the superconducting dome in iron-pnictides
• Localization of preformed Cooper-pairs in disordered superconductors
• Gate-induced superconductivity in a monolayer topological insulator
• Nature of the superconductor-insulator transition in disordered superconductors
• Disorder-Induced Inhomogeneities of the Superconducting State Close to the Superconductor-Insulator Transition
• Nature of the Quantum Metal in a Two-Dimensional Crystalline Superconductor
• Metallic ground state in an ion-gated two-dimensional superconductor
• Quantum criticality in ferroelectrics
• Ubiquitous signatures of nematic quantum criticality in optimally doped Fe-based superconductors
• Universal $T$-linear resistivity and Planckian limit in overdoped cuprates
• Direct observation of high temperature superconductivity in one-unit-cell FeSe films
• Infinite-randomness quantum Ising critical fixed points
• Quantum criticality with two length scales
• Instabilities and disorder-driven first-order transition of the vortex lattice
• Dynamic instabilities and memory effects in vortex matter
• A ferroelectric quantum phase transition inside the superconducting dome of Sr${}_{1-x}$Ca${}_x$TiO${}_{3-\delta }$
• Dephasing of Electrons in Mesoscopic Metal Wires
• Ising Superconductivity and Quantum Phase Transition in Macro-Size Monolayer NbSe2
• Dissipation effects on the superconductor-insulator transition in 2-D superconductors
• A Numerical Study of the Random Transverse-Field Ising Spin Chain
• Imaging of super-fast dynamics and flow instabilities of superconducting vortices
• Anomalous metals -- failed superconductors
• Linear in Temperature Resistivity and Associated Mysteries
• Single and two-particle energy gaps across the disorder-driven superconductor-insulator transition
• Strange metal behavior in a pure ferromagnetic Kondo lattice
• The Elusive Bose Metal
• Electric field control of disorder-tunable superconductivity and the emergence of quantum metal at an oxide interface
• Quantum Griffiths effects and smeared phase transitions in metals: theory and experiment
• Quantum coherence across bosonic superconductor-anomalous metal-insulator transitions
• Quantum breakdown of superconductivity in low-dimensional materials
• Transport Through Quantum Melts
• On the existence of a Bose Metal at T=0
• Critical Behavior and Griffiths-McCoy Singularities in the Two-Dimensional Random Quantum Ising Ferromagnet
• Evidence for a common physical description of non-Fermi-liquid behavior in f-electron systems
• Approaching Zero-Temperature Metallic States in Mesoscopic Superconductor-Normal-Superconductor Arrays
• Theory of quantum metal to superconductor transitions in highly conducting systems
• Kondo-Cluster-Glass State near a Ferromagnetic Quantum Phase Transition
• Topological spin Hall states, charged skyrmions, and superconductivity in two dimensions
• Quantum Griffiths Phase in the weak itinerant ferromagnetic alloy Ni${}_{1-x}$V${}_x$
• Detection of a superconducting phase in a two-atom layer of hexagonal Ga film grown on semiconducting GaN(0001)
• Universal scaling of the critical temperature and the strange-metal scattering rate in unconventional superconductors
• Magnetically Induced Metallic Phase in Superconducting Tantalum Films
• Renormalization group study of the two-dimensional random transverse-field Ising model
• Emergence of superconductivity in the canonical heavy-electron metal YbRh2Si2
• Disorder in quantum many-body systems
• Effect of disorder on quantum phase transitions in anisotropic XY spin chains in a transverse field
• Superconducting, Insulating, and Anomalous Metallic Regimes in a Gated Two-Dimensional Semiconductor-Superconductor Array
• Effects of dissipation on quantum phase transitions
• Properties of MgB2 thin films with carbon doping
• Quantum Superconductor-Metal Transition in a 2D Proximity-Coupled Array
• Effects of dissipation on a quantum critical point with disorder
• Superconducting fluctuations at low temperature
• Theory of the Quantum Critical Fluctuations in Cuprates
• The density and disorder tuned superconductor-metal transition in two dimensions
• Infinite-randomness quantum critical points induced by dissipation
• Infinite disorder scaling of random quantum magnets in three and higher dimensions
• Quantum phase transitions in highly crystalline two-dimensional superconductors
• Universal conductance of nanowires near the superconductor-metal quantum transition
• Extreme Sensitivity of the Superconducting State in Thin Films
• Vortices and quasiparticles near the "superconductor-insulator" transition in thin films
• Exact results for quantum phase transitions in random XY spin chains
• Two-stage magnetic-field-tuned superconductor-insulator transition in underdoped La${}_{2-x}$Sr${}_x$CuO${}_4$
• Quantum superconductor-metal transition
• Type-II Ising superconductivity and anomalous metallic state in macro-size ambient-stable ultrathin crystalline films
• Criticality and quenched disorder: rare regions vs. Harris criterion
• Proximate deconfined quantum critical point in SrCu2(BO3)2
• True Superconductivity in a 2D "Superconducting-Insulating" System
• A Phase Glass is a Bose Metal: New Conducting State in 2D
• Particle-hole symmetry reveals failed superconductivity in the metallic phase of two-dimensional superconducting films
• A strange metal in a bosonic system
• Fidelity approach to the disordered quantum XY model
• Electronically driven superconductor insulator transition in electrostatically doped La${}_2$CuO${}_{4+\delta }$ thin films
• High harmonic spectroscopy of quantum phase transitions in a high-T${}_c$ superconductor
• Observation of Quantum Griffiths Singularity and Ferromagnetism at Superconducting LaAlO3/SrTiO3(110) Interface
• Fluctuoscopy of Disordered Two-Dimensional Superconductors
• Quantum Criticality in doped CePd_1-xRh_x Ferromagnet
• Quantum-Critical Fluctuations in 2D Metals: Strange Metals and Superconductivity in Antiferromagnets and in Cuprates
• Quantum Griffiths phase inside the ferromagnetic phase of Ni${}_{1-x}$V${}_x$
• Interface induced Zeeman-protected superconductivity in ultrathin crystalline lead films
• Self Duality and a possible Hall-insulator phase near the superconductor-to-insulator transition in two-dimensional indium-oxide films
• Infinite randomness fixed point of the superconductor-metal quantum phase transition
• Coexistence of resistance oscillations and the anomalous metal phase in a lithium intercalated TiSe${}_2$ superconductor
• Anomalous Metallic Phase in Tunable Destructive Superconductors
• Extrinsic and Intrinsic Anomalous Metallic States in Transition Metal Dichalcogenide Ising Superconductors
• The observation of in-plane quantum Griffiths singularity in two-dimensional crystalline superconductors
• Absence of dissipationless transport in clean 2D superconductors
• Composite fermions and the field-tuned superconductor-insulator transition
• Microwave Spectroscopy Evidence of Superconducting Pairing in the Magnetic-Field-Induced Metallic State of InO${}_x$ Films at Zero Temperature
• Quantum and classical ratchet motions of vortices in a 2D trigonal superconductor
• Dynamical conductivity at the dirty superconductor-metal quantum phase transition
• Infinite-randomness fixed point of the quantum superconductor-metal transitions in amorphous thin films
• Unconventional Superconducting Quantum Criticality in Monolayer WTe2
• Giant Nernst effect in the crossover between Fermi liquid and strange metal
• Anomalous quantum Griffiths singularity in ultrathin crystalline lead films
• Anomalous quantum metal in a 2D crystalline superconductor with intrinsic electronic non-uniformity
• Superconductor-metal quantum transition at the EuO-KTaO3 interface
• Anomalous metals: from "failed superconductor" to "failed insulator"
• Hot Electron Effects in the 2D Superconductor-Insulator Transition
• Theory of the pairbreaking superconductor-metal transition in nanowires
• Signatures of a Quantum Griffiths Phase close to an Electronic Nematic Quantum Phase Transition
• Universal behavior of the bosonic metallic ground state in a two-dimensional superconductor
• Pair-breaking quantum phase transition in superconducting nanowires
• Absence of cyclotron resonance in the anomalous metallic phase in InO${}_x$
• Piezo-driven sample rotation system with ultra-low electron temperature
• Free at Last: Bose Metal Uncaged
• Robust anomalous metallic states and vestiges of self duality in two-dimensional granular In-InOx composites
• Thermal expansion and Grueneisen parameter in quantum Griffiths phases
• Effect of external electromagnetic radiation on the anomalous metallic behaviors in Ta thin films
• The activated scaling behavior of quantum Griffiths singularity in two-dimensional superconductors

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• Unveiling resilient superconducting fluctuations in atomically thin NbSe${}_2$ through Higgs mode spectroscopy
• Warm Inflation with Barrow Holographic Dark Energy
• Quantum Griffiths singularity in a three-dimensional superconductor to Anderson critical insulator transition
• Voltage-tuned anomalous-metal to metal transition in hybrid Josephson junction arrays
• Point-contact Andreev reflection spectroscopy of layered superconductors with device-integrated diamond anvil cells
• Interfacial superconductivity in Cu/Cu${}_2$O and its effect on shielding ambient electric fields
• Tuning of superconducting properties with disorder in NbxSn nanocrystalline thin films
• Anomalous terahertz nonlinearity in disordered s-wave superconductor close to the superconductor-insulator transition
• Spectroscopic evidence of disorder-induced quantum phase transitions in monolayer Fe(Te,Se) superconductor
• Random transverse and longitudinal field Ising chains
• Divergence of thermalization rates driven by the competition between finite temperature and quantum coherence
• Quantum Griffiths singularity in three-dimensional MoTiN superconducting films
• Low-dimensional platforms for single photon detection