scholarly journals Rise and fall of Landau’s quasiparticles while approaching the Mott transition

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Andrej Pustogow ◽  
Yohei Saito ◽  
Anja Löhle ◽  
Miriam Sanz Alonso ◽  
Atsushi Kawamoto ◽  
...  
Keyword(s):  
Fermi Liquid ◽  
Mott Transition ◽  
Dynamical Localization ◽  
Strong Increase ◽  
Unconventional Superconductors ◽  
Scattering Rate ◽  
Complex Interactions ◽  
Liquid Behavior ◽  
Half Filling ◽  
Correlation Strength

AbstractLandau suggested that the low-temperature properties of metals can be understood in terms of long-lived quasiparticles with all complex interactions included in Fermi-liquid parameters, such as the effective mass m⋆. Despite its wide applicability, electronic transport in bad or strange metals and unconventional superconductors is controversially discussed towards a possible collapse of the quasiparticle concept. Here we explore the electrodynamic response of correlated metals at half filling for varying correlation strength upon approaching a Mott insulator. We reveal persistent Fermi-liquid behavior with pronounced quadratic dependences of the optical scattering rate on temperature and frequency, along with a puzzling elastic contribution to relaxation. The strong increase of the resistivity beyond the Ioffe–Regel–Mott limit is accompanied by a ‘displaced Drude peak’ in the optical conductivity. Our results, supported by a theoretical model for the optical response, demonstrate the emergence of a bad metal from resilient quasiparticles that are subject to dynamical localization and dissolve near the Mott transition.

scholarly journals Hidden non-Fermi liquid behavior caused by magnetic phase transition in Ni-doped Ba-122 pnictides

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Seokbae Lee ◽  
Ki-Young Choi ◽  
Eilho Jung ◽  
Seulki Roh ◽  
Soohyeon Shin ◽  
...  
Keyword(s):  
Phase Transition ◽  
Temperature Dependence ◽  
Magnetic Phase Transition ◽  
Fermi Liquid ◽  
Magnetic Phase ◽  
Linear Temperature Dependence ◽  
Scattering Rate ◽  
Underdoped Sample ◽  
Liquid Behavior ◽  
Fermi Liquid Behavior

Abstract We studied two BaFe2−x Ni x As2 (Ni-doped Ba-122) single crystals at two different doping levels (underdoped and optimally doped) using an optical spectroscopic technique. The underdoped sample shows a magnetic phase transition around 80 K. We analyze the data with a Drude-Lorentz model with two Drude components (D1 and D2). It is known that the narrow D1 component originates from electron carriers in the electron-pockets and the broad D2 mode is from hole carriers in the hole-pockets. While the plasma frequencies of both Drude components and the static scattering rate of the broad D2 component show negligible temperature dependencies, the static scattering rate of the D1 mode shows strong temperature dependence for the both samples. We observed a hidden quasi-linear temperature dependence in the scattering rate of the D1 mode above and below the magnetic transition temperature while in the optimally doped sample the scattering rate shows a more quadratic temperature dependence. The hidden non-Fermi liquid behavior in the underdoped sample seems to be related to the magnetic phase of the material.

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.

NUMERICAL SIMULATION OF THE 1D AND 2D HUBBARD MODELS: FERMI LIQUID BEHAVIOR AND ITS BREAKDOWN

1988 ◽  
Vol 02 (05) ◽  
pp. 993-1003 ◽  
Author(s):  
S. Sorella ◽  
E. Tosatti ◽  
S. Baroni ◽  
R. Car ◽  
M. Parrinello
Keyword(s):  
Ground State ◽  
Fermi Liquid ◽  
Finite Size ◽  
Simulation Method ◽  
Square Lattice ◽  
Antiferromagnetic Order ◽  
Hubbard Models ◽  
Clear Sign ◽  
Liquid Behavior ◽  
Half Filling

The ground state of the 1D and of the 2D (square lattice) finite-size Hubbard model is investigated for variable filling using a novel quantum simulation method. We have studied up to 256 sites for both 1D and 2D. Away from half filling the 2D antiferromagnetic order is initially destroyed, albeit without any clear sign of a Fermi liquid behaviour. A metallic jump in n(k) appears only very far from half filling. In the 1D case, by contrast, a Fermi liquid-like jump in n(k) is obtained even very close to half filling.

scholarly journals Breakdown of semiclassical description of thermoelectricity in near-magic angle twisted bilayer graphene

2021 ◽  
Author(s):  
Bhaskar Ghawri ◽  
Phanibhusan Mahapatra ◽  
Manjari Garg ◽  
Shinjan Mandal ◽  
Saisab Bhowmik ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Low Temperatures ◽  
Fermi Liquid ◽  
Bilayer Graphene ◽  
Magic Angle ◽  
Relative Rotation ◽  
Scattering Rate ◽  
Band Filling ◽  
Half Filling ◽  
Twisted Bilayer Graphene

Abstract The planar assembly of twisted bilayer graphene (tBLG) hosts a multitude of interaction-driven phases when the relative rotation is close to the magic angle (θ = 1.1°). This includes correlation-induced ground states that reveal spontaneous symmetry breaking at low temperature, as well as the possibility of non-Fermi liquid (NFL) excitations. However, experimentally, the manifestation of NFL effects in transport properties of twisted bilayer graphene remains ambiguous. Here we report simultaneous measurements of electrical resistivity (ρ) and thermoelectric power (S) in tBLG for several twist angles between θ ≈ 1.0°-1.7°. We observe an emergent violation of the semiclassical Mott relation in the form of excess S close to half-filling for θ≈1.6° that vanishes for ≥ 2°. The excess S (≈2 μV/K at low temperatures T ≈10 K at θ≈1.6°) persists up to ≈ 40 K and is accompanied by metallic T-linear ρ with transport scattering rate (1/τ) of near-Planckian magnitude 1/τ ≈ k_BT/h_bar. Closer to θ_m, the excess S was also observed for fractional band-filling (ν≈ 0.5). The combination of non-trivial electrical transport and violation of Mott relation provides compelling evidence of NFL physics intrinsic to tBLG.

EVALUATION OF THE PSEUDOGAP IN THE TWO-DIMENSIONAL PAIRING MODEL

2003 ◽  
Vol 17 (29n30) ◽  
pp. 1501-1515
Author(s):  
EUGEN-VICTOR MACOCIAN
Keyword(s):  
Fermi Liquid ◽  
Characteristic Temperature ◽  
The Self ◽  
Two Dimensional ◽  
Pairing Mechanism ◽  
Self Energy ◽  
Self Consistent ◽  
Liquid Behavior ◽  
Half Filling ◽  
Pairing Model

In this article, we perform a self-consistent calculation for the self-energy, based on the pairing mechanism for the two-dimensional phenomenological model below half filling. The non-Fermi versus Fermi liquid behavior is analyzed and the self-energies are compared. We also investigate the doping dependence of the pseudogap in the underdoped regime of the phase diagram of cuprates superconductors. Comparing the obtained results with experimental data, it is found that Δpg scales with characteristic temperature T*.

scholarly journals Magnetotransport of dirty-limit van Hove singularity quasiparticles

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yang Xu ◽  
František Herman ◽  
Veronica Granata ◽  
Daniel Destraz ◽  
Lakshmi Das ◽  
...  
Keyword(s):  
Electron Scattering ◽  
Fermi Liquid ◽  
Inelastic Electron ◽  
Density Of State ◽  
Strontium Ruthenate ◽  
Van Hove Singularity ◽  
Strong Variation ◽  
Electronic Density ◽  
Dirty Limit ◽  
Liquid Behavior

AbstractTuning of electronic density-of-states singularities is a common route to unconventional metal physics. Conceptually, van Hove singularities are realized only in clean two-dimensional systems. Little attention has therefore been given to the disordered (dirty) limit. Here, we provide a magnetotransport study of the dirty metamagnetic system calcium-doped strontium ruthenate. Fermi liquid properties persist across the metamagnetic transition, but with an unusually strong variation of the Kadowaki-Woods ratio. This is revealed by a strong decoupling of inelastic electron scattering and electronic mass inferred from density-of-state probes. We discuss this Fermi liquid behavior in terms of a magnetic field tunable van Hove singularity in the presence of disorder. More generally, we show how dimensionality and disorder control the fate of transport properties across metamagnetic transitions.

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