Heavy Fermions: Electrons at the Edge of Magnetism

Coleman, Piers

doi:10.1002/9780470022184.hmm105

Cited by 138 publications

(162 citation statements)

References 214 publications

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“…The implementation of the two-band SU(N) Hubbard model with alkaline earth atoms opens untapped opportunities [22,140,141], including the implementation of a SU(N) generalization of the SU(2)-Kondo lattice model (one of the canonical models used to study strongly correlated electron systems, such as manganese oxide perovskites [142] and rare-earth and actinide compounds classed as heavy-fermion materials [143]) and a SU(N) generalization of the N=2 Kugel-Khomskii Hamiltonian (used to model the spinorbital interactions in transition-metal oxides with the perovskite structure [144]). Just recently it was also pointed out that a SU(N)-Mott insulator with one ground state atoms and one excited state atoms on each site of a square lattice is likely to realize a non-Abelian Chiral spin liquid with a quantum statistics sufficient for universal quantum computations [125,145].…”

Section: A Orbital Magnetismmentioning

confidence: 99%

Ultracold Fermi gases with emergent SU(N) symmetry

2014

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We review recent experimental and theoretical progress on ultracold alkaline-earth Fermi gases with emergent SU(N ) symmetry. Emphasis is placed on describing the ground-breaking experimental achievements of recent years. The latter include the cooling to below quantum degeneracy of various isotopes of ytterbium and strontium, the demonstration of optical Feshbach resonances and the optical Stern-Gerlach effect, the realization of a Mott insulator of 173 Yb atoms, the creation of various kinds of Fermi-Bose mixtures and the observation of many-body physics in optical lattice clocks. On the theory side, we survey the zoo of phases that have been predicted for both gases in a trap and loaded into an optical lattice, focusing on two and three-dimensional systems. We also discuss some of the challenges that lie ahead for the realization of such phases, such as reaching the temperature scale required to observe magnetic and more exotic quantum orders, and dealing with collisional relaxation of excited electronic levels.

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Section: A Orbital Magnetismmentioning

confidence: 99%

Ultracold Fermi gases with emergent SU(N) symmetry

2014

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“…3 In particular, the physical and structural properties of these materials have not only helped to further develop the concepts of quantum phase transitions and non-Fermi liquids, but have also motivated theoretical studies of exotic mechanisms for unconventional superconductivity. Moreover, it has been shown recently that f -orbital compounds may host topologically non-trivial electronic states.…”

Section: Introductionmentioning

confidence: 99%

Pressure studies of the quantum critical alloyCe0.93Yb0.07CoIn5

et al. 2015

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Here we present our experimental and theoretical study of the effects of pressure on the transport properties of the heavy-fermion alloy Ce1−xYbxCoIn5 with actual concentration x ≈ 0.07. We specifically choose this value of ytterbium concentration because the magnetic-field-induced quantum critical point, which separates the antiferromagnetic and paramagnetic states at zero temperature, approaches zero, as has been established in previous studies. Our measurements show that pressure further suppresses quantum fluctuations in this alloy, just as it does in the parent compound CeCoIn5. In contrast, the square-root temperature dependent part of resistivity remains insensitive to pressure, indicating that the heavy-quasiparticles are not involved in the inelastic scattering processes leading to such a temperature dependent resistivity. We demonstrate that the growth of the coherence temperature with pressure, as well as the decrease of the residual resistivity, can be accurately described by employing the coherent potential approximation for a disordered Kondo lattice.

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“…Thermodynamic and transport studies have long provided evidence for heavy quasiparticles, their unconventional superconductivity and non-Fermi-liquid behaviour in a variety of material systems [9][10][11][12][13][14] . However, the emergence of a coherent band of heavy quasiparticles near the Fermi energy in a Kondo lattice system is still not well understood [14][15][16][17] . Part of the challenge has been the inability of spectroscopic measurements to probe the development of heavy quasiparticles with lowering of temperature and to characterize their properties with high energy resolution.…”

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confidence: 99%

Visualizing heavy fermions emerging in a quantum critical Kondo lattice

Aynajian

Neto

Gyenis

et al. 2012

Nature

205

211

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In solids containing elements with f orbitals, the interaction between f-electron spins and those of itinerant electrons leads to the development of low-energy fermionic excitations with a heavy effective mass. These excitations are fundamental to the appearance of unconventional superconductivity and non-Fermi-liquid behaviour observed in actinide- and lanthanide-based compounds. Here we use spectroscopic mapping with the scanning tunnelling microscope to detect the emergence of heavy excitations with lowering of temperature in a prototypical family of cerium-based heavy-fermion compounds. We demonstrate the sensitivity of the tunnelling process to the composite nature of these heavy quasiparticles, which arises from quantum entanglement of itinerant conduction and f electrons. Scattering and interference of the composite quasiparticles is used to resolve their energy-momentum structure and to extract their mass enhancement, which develops with decreasing temperature. The lifetime of the emergent heavy quasiparticles reveals signatures of enhanced scattering and their spectral lineshape shows evidence of energy-temperature scaling. These findings demonstrate that proximity to a quantum critical point results in critical damping of the emergent heavy excitation of our Kondo lattice system.Comment: preprint version, 26 pages, 6 figures. Supplementary: 15 pages, 14 figure

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Heavy Fermions: Electrons at the Edge of Magnetism

Abstract: An introduction to the physics of heavy‐fermion compounds is presented, highlighting the conceptual developments and emphasizing the mysteries and open questions that persist in this active field of research.

Cited by 138 publications

References 214 publications

Ultracold Fermi gases with emergent SU(N) symmetry

Ultracold Fermi gases with emergent SU(N) symmetry

Pressure studies of the quantum critical alloyCe0.93Yb0.07CoIn5

Visualizing heavy fermions emerging in a quantum critical Kondo lattice

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