scholarly journals Linear resistivity and Sachdev-Ye-Kitaev (SYK) spin liquid behavior in a quantum critical metal with spin-1/2 fermions

2020 ◽  
Vol 117 (31) ◽  
pp. 18341-18346 ◽  
Author(s):  
Peter Cha ◽  
Nils Wentzell ◽  
Olivier Parcollet ◽  
Antoine Georges ◽  
Eun-Ah Kim
Keyword(s):  
Fermi Liquid ◽  
Spin Dynamics ◽  
Quantum Critical Point ◽  
Quantum Spin ◽  
Spin Interaction ◽  
Spin Liquid ◽  
Spin Glass Phase ◽  
Scattering Rate ◽  
Liquid Behavior ◽  
Quantum Critical

“Strange metals” with resistivity depending linearly on temperature T down to low T have been a long-standing puzzle in condensed matter physics. Here, we consider a lattice model of itinerant spin-1/2fermions interacting via onsite Hubbard interaction and random infinite-ranged spin–spin interaction. We show that the quantum critical point associated with the melting of the spin-glass phase by charge fluctuations displays non-Fermi liquid behavior, with local spin dynamics identical to that of the Sachdev-Ye-Kitaev family of models. This extends the quantum spin liquid dynamics previously established in the large-M limit ofSU(M)symmetric models to models with physicalSU(2)spin-1/2electrons. Remarkably, the quantum critical regime also features a Planckian linear-T resistivity associated with a T-linear scattering rate and a frequency dependence of the electronic self-energy consistent with the marginal Fermi liquid phenomenology.

NON-FERMI LIQUID BEHAVIOR IN THE SINGLE-IMPURITY MIXED VALENCE PROBLEM

1995 ◽  
Vol 09 (23) ◽  
pp. 1527-1533
Author(s):  
GUANG-MING ZHANG ◽  
ZHAO-BIN SU ◽  
LU YU
Keyword(s):  
Critical Point ◽  
Fermi Liquid ◽  
Mixed Valence ◽  
Quantum Critical Point ◽  
Coulomb Interactions ◽  
Single Impurity ◽  
Liquid Behavior ◽  
New Type ◽  
Quantum Critical ◽  
Fermi Liquid Behavior

An effective Hamiltonian of the Anderson single-impurity model with finite-range Coulomb interactions is derived near a particular limit, which is analogous to the Toulouse limit of the ordinary Kondo problem, and the physical properties around the mixed valence quantum critical point are calculated. At this quantum critical point, the local moment is only partially quenched and X-ray edge singularities are exhibited. Around this point, a new type of non-Fermi liquid behavior is predicted with an extra specific heat C imp ~ T1/4 + AT ln T and spin-susceptibility χ imp ~T−3/4 + B ln T.

scholarly journals Giant isotropic magneto-thermal conductivity of metallic spin liquid candidate Pr2Ir2O7 with quantum criticality

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J. M. Ni ◽  
Y. Y. Huang ◽  
E. J. Cheng ◽  
Y. J. Yu ◽  
B. L. Pan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Critical Point ◽  
Quantum Critical Point ◽  
Magnetic Monopoles ◽  
Quantum Criticality ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Zero Field ◽  
Spin Liquids ◽  
Quantum Critical

AbstractSpin liquids are exotic states with no spontaneous symmetry breaking down to zero-temperature because of the highly entangled and fluctuating spins in frustrated systems. Exotic excitations like magnetic monopoles, visons, and photons may emerge from quantum spin ice states, a special kind of spin liquids in pyrochlore lattices. These materials usually are insulators, with an exception of the pyrochlore iridate Pr2Ir2O7, which was proposed as a metallic spin liquid located at a zero-field quantum critical point. Here we report the ultralow-temperature thermal conductivity measurements on Pr2Ir2O7. The Wiedemann–Franz law is verified at high fields and inferred at zero field, suggesting no breakdown of Landau quasiparticles at the quantum critical point, and the absence of mobile fermionic excitations. This result puts strong constraints on the description of the quantum criticality in Pr2Ir2O7. Unexpectedly, although the specific heats are anisotropic with respect to magnetic field directions, the thermal conductivities display the giant but isotropic response. This indicates that quadrupolar interactions and quantum fluctuations are important, which will help determine the true ground state of this material.

scholarly journals Superconductivity and non-Fermi liquid behavior near a nematic quantum critical point

2017 ◽  
Vol 114 (19) ◽  
pp. 4905-4910 ◽  
Author(s):  
Samuel Lederer ◽  
Yoni Schattner ◽  
Erez Berg ◽  
Steven A. Kivelson
Keyword(s):  
Critical Point ◽  
Transition Metal Oxides ◽  
Quantum Monte Carlo ◽  
Fermi Liquid ◽  
Quantum Critical Point ◽  
Low Frequency ◽  
Critical Fluctuations ◽  
Liquid Behavior ◽  
Quantum Critical ◽  
Fermi Liquid Behavior

Using determinantal quantum Monte Carlo, we compute the properties of a lattice model with spin 12 itinerant electrons tuned through a quantum phase transition to an Ising nematic phase. The nematic fluctuations induce superconductivity with a broad dome in the superconducting Tc enclosing the nematic quantum critical point. For temperatures above Tc, we see strikingly non-Fermi liquid behavior, including a “nodal–antinodal dichotomy” reminiscent of that seen in several transition metal oxides. In addition, the critical fluctuations have a strong effect on the low-frequency optical conductivity, resulting in behavior consistent with “bad metal” phenomenology.

scholarly journals Spin liquid and ferroelectricity close to a quantum critical point in PbCuTe2O6

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Christian Thurn ◽  
Paul Eibisch ◽  
Arif Ata ◽  
Maximilian Winkler ◽  
Peter Lunkenheimer ◽  
...  
Keyword(s):  
Quantum Critical Point ◽  
Quantum Fluctuations ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Spin Liquids ◽  
Range Magnetic Order ◽  
Powder Samples ◽  
Quantum Critical ◽  
Quantum Spin Liquid ◽  
Long Range Magnetic Order

AbstractGeometrical frustration among interacting spins combined with strong quantum fluctuations destabilize long-range magnetic order in favor of more exotic states such as spin liquids. By following this guiding principle, a number of spin liquid candidate systems were identified in quasi-two-dimensional (quasi-2D) systems. For 3D, however, the situation is less favorable as quantum fluctuations are reduced and competing states become more relevant. Here we report a comprehensive study of thermodynamic, magnetic and dielectric properties on single crystalline and pressed-powder samples of PbCuTe2O6, a candidate material for a 3D frustrated quantum spin liquid featuring a hyperkagome lattice. Whereas the low-temperature properties of the powder samples are consistent with the recently proposed quantum spin liquid state, an even more exotic behavior is revealed for the single crystals. These crystals show ferroelectric order at TFE ≈ 1 K, accompanied by strong lattice distortions, and a modified magnetic response—still consistent with a quantum spin liquid—but with clear indications for quantum critical behavior.

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