Quantum phase transition in a single-molecule quantum dot

Abstract

Quantum criticality is the intriguing possibility offered by the laws of quantum mechanics when the wave function of a many-particle physical system is forced to evolve continuously between two distinct, competing ground states. This phenomenon, often related to a zero-temperature magnetic phase transition, can be observed in several strongly correlated materials such as heavy fermion compounds or possibly high-temperature superconductors, and is believed to govern many of their fascinating, yet still unexplained properties. In contrast to these bulk materials with very complex electronic structure, artificial nanoscale devices could offer a new and simpler vista to the comprehension of quantum phase transitions. This long-sought possibility is demonstrated by our work in a fullerene molecular junction, where gate voltage induces a crossing of singlet and triplet spin states at zero magnetic field. Electronic tunneling from metallic contacts into the ${\mathrm{C}}_{60}$ quantum dot provides here the necessary many-body correlations to observe a true quantum critical behavior.

8 pages, 5 figures

References in corpus (11)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Quantum magnetism and criticality
• Observation of the two-channel Kondo effect
• The Kondo effect in C${}_{60}$ single-molecule transistors
• Tuning the Kondo effect with a mechanically controllable break junction
• Strongly correlated regimes in a double quantum-dot device
• Nonequilibrium Singlet-Triplet Kondo Effect in Carbon Nanotubes
• Quantum criticality in a double quantum-dot system
• Electronic Transport Spectroscopy of Carbon Nanotubes in a Magnetic Field
• Feedback controlled electromigration in four-terminal nano-junctions
• Kondo Effect in Mesoscopic Quantum Dots

Cited by in corpus (10)

• Tunneling Spectra of Individual Magnetic Endofullerene Molecules
• A benzene interference single-electron transistor
• Correlated electron physics in multilevel quantum dots: phase transitions, transport, and experiment
• Josephson Effect through an isotropic magnetic molecule
• Tunable pseudogap Kondo effect and quantum phase transitions in Aharonov-Bohm interferometers
• Finite-temperature conductance signatures of quantum criticality in double quantum dots
• Optimal broadening of finite energy spectra in the numerical renormalization group: application to dissipative dynamics in two-level systems
• Kondo effect and channel mixing in oscillating molecules
• Out-of-equilibrium singlet-triplet Kondo effect in a single C_60 quantum dot
• Kondo effects in a C_60 single-molecule transistor