Unconventional quantum criticality emerging as a new common language of transition-metal compounds, heavy-fermion systems, and organic conductors

Abstract

We analyze and overview several different unconventional quantum criticalities. One origin of the unconventionality is the proximity to first-order transitions. The border between the first-order and continuous transitions is described by a quantum tricritical point (QTCP) for symmetry-breaking transitions. One of the characteristic features is the concomitant divergence of order-parameter and uniform fluctuations in contrast to the conventional quantum critical point (QCP). Several puzzling non-Fermi-liquid properties are referred to be accounted for as in the cases of YbRh2Si2, CeRu2Si2 and beta-YbAlB4. Another more dramatic unconventionality appears in this case for topological transitions such as metal-insulator and Lifshitz transitions. This border, the marginal quantum critical point (MQCP), belongs to an unprecedented universality class with diverging uniform fluctuations at zero temperature. The MQCP has a unique feature by a combined character of symmetry-breaking and topological transitions. The theoretical results are supported by experimental indications for V2-xCrxO3 and an organic conductor kappa-(ET)2Cu[N(CN)2]Cl. Identifying topological transitions also reveals how non-Fermi liquid appears as a phase in metals. The theory also accounts for the criticality of a metamagnetic transition in ZrZn2, by interpreting it as an interplay of Lifshitz transition and correlation effects. We discuss common underlying physics in these examples.

18 pages including 4 figures, published in J. Phys.: Condens. Matter 22 (2010) 164206

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Cited by in corpus (26)

• Review of U-based Ferromagnetic Superconductors: Comparison between UGe2, URhGe, and UCoGe
• Metamagnetic Transition in Heavy Fermion Superconductor UTe2
• Lifshitz Transition in the Two Dimensional Hubbard Model
• Scaling theory of the Mott transition and breakdown of the Grüneisen scaling near a finite-temperature critical end point
• Importance of subleading corrections for the Mott critical point
• Collapse of ferromagnetism and Fermi surface instability near reentrant superconductivity of URhGe
• Preformed Excitons, Orbital Selectivity, and Charge-Density-Wave Order in 1T-TiSe_2
• Mott metal-insulator transition on compressible lattices
• Unconventional Strong Spin-Fluctuation Effects around the Critical Pressure of the Itinerant Ising-Type Ferromagnet URhAl
• Evolution of the Superconductivity Dome in the two dimensional Hubbard Model
• Indication of Ferromagnetic Quantum Critical Point in Kondo Lattice CeRh${}_6$Ge${}_4$
• Pressure-Driven Quantum Criticality and T/H Scaling in the Icosahedral Au-Al-Yb Approximant
• Chemically-Mediated quantum criticality in NbFe_2
• Thermoelectric transport across the metamagnetic transition of CeRu2Si2
• Role of the van Hove Singularity in the Quantum Criticality of the Hubbard Model
• Shape resonances in multi-condensate granular superconductors formed by networks of nanoscale-striped puddles
• The road map toward room temperature superconductivity: manipulating different pairing channels in systems composed of multiple electronic components
• Scaling theory for Mott-Hubbard transitions
• Charge and spin criticality for the continuous Mott transition in a two-dimensional organic conductor
• Probing the Mott Physics in $\kappa$-(BEDT-TTF)${}_2$X Salts via Thermal Expansion
• Universality Class of the Mott Transition
• Mott Quantum Criticality in the Anisotropic 2D Hubbard Model
• Phase Diagram Structure of Topological Mott Transition for Zero-gap Semiconductors beyond Conventional Landau-Ginzburg-Wilson Scenario
• Temperature-induced spontaneous time-reversal symmetry breaking on the honeycomb lattice
• Lifshitz transition in two-dimensional spin-density wave models
• Quantum Critical Phase and Lifshitz Transition in an Extended Periodic Anderson Model