Glassy Behavior of Electrons Near Metal-Insulator Transitions

Abstract

The emergence of glassy behavior of electrons is investigated for systems close to disorder-driven and interaction-driven metal-insulator transitions. Our results indicate that Anderson localization effects strongly stabilize such glassy behavior, while Mott localization tends to suppress it. We predict the emergence of an intermediate metallic glassy phase separating the insulator from the normal metal. This effect is expected to be most pronounced for sufficiently disordered systems, in agreement with recent experimental observations.

Quantum charge glasses of itinerant fermions with cavity-mediated long-range interactions

“…The Anderson delocalization of the fermionic quasiparticles may precede the melting of the glass, in which case we obtain a metallic glass with non-zero conductivity at zero temperature. Such a glassy state with metallic conduction was obtained in dynamical mean field theory by Dobrosavljevic and collaborators [33,34]. Moreover, the fact that glassy phases may also exist in phases with good transport properties was recently shown in models of frustrated bosons [18,42,43] where a 'superglass' phase with microscopically coexisting superfluid and glassy density order exists.…”

Self-generated electronic heterogeneity and quantum glassiness in the high-temperature superconductors

“…The emergence of such an intermediate conducting glass phase separating a conventional metal and a glassy insulator has, in fact, been predicted in recent theoretical work [7].…”

“…Typically, a large number of possible configurations of these local regions have comparable energies, resulting in slow relaxation, aging, and other signatures of glassy systems. Because the stability of such ordering is controlled by doping-dependent quantum fluctuations [6,7] introduced by itinerant carriers, these systems can be regarded as prototypical quantum glasses -a new paradigm of strongly correlated matter.In this Letter we report the emergence and evolution of dynamical heterogeneity and glassy behavior across the phase diagram of the high-transition-temperature (T c ) superconductors (HTS). Based on data of the spin and charge dynamics, we draw a phase diagram (Fig.…”

“…Coulomb interactions, however, enforce charge neutrality and prevent [4] global phase separation; instead, the carriers are expected [5] to segregate into nano-scale domains -to form a stripe/cluster glass [5]. As quantum fluctuations increase upon doping [6,7], such a glassy phase should be eventually suppressed at a quantum critical point, which in LSCO emerges around x = x opt ≈ 0.2. Remarkable independent evidence that a QCP is found precisely at x = x opt is provided by the observation of a sharp change in the superfluid density n s (0) ∼ 1/λ 2 ab (0) (where λ ab (0) is the absolute value of the in-plane penetration depth).…”

Memory effect in electron glasses: Theoretical analysis via a percolation approach

“…First attempts towards a theoretical description of glassiness in the regime close to the transition were undertaken in Refs. 60,61 . At this point it remains an interesting open question, both theoretically and experimentally, whether the onset of metastability and glassiness coincides with the transition to the insulator, and, if so, what role the glassy freezing plays in the physics of the metal-insulator transition.…”