Bose metal: Gauge-field fluctuations and scaling for field-tuned quantum phase transitions

Abstract

In this paper, we extend our previous discussion of the Bose metal to the field tuned case. We point out that the recent observation of the metallic state as an intermediate phase between the superconductor and the insulator in the field tuned experiments on MoGe films is in perfect consistency with the Bose metal scenario. We establish a connection between general dissipation models and gauge field fluctuations and apply this to a discussion of scaling across the quantum phase boundaries of the Bose metallic state. Interestingly, we find that the Bose metal scenario implies a possible two parameter scaling for resistivity across the Bose metal-insulator transition, which is remarkably consistent with the MoGe data. Scaling at the superconductor-metal transition is also proposed, and a phenomenolgical model for the metallic state is discussed. The effective action of the Bose metal state is described and its low energy excitation spectrum is found to be ω ∝ k 3 .

Universal magnetic-field-driven metal-insulator-metal transformations in graphite and bismuth

“…On the other hand, it has been demonstrated in Ref. [33,34] that MIT in graphite can be formally described in terms of the phenomenological two-parameter scaling approach introduced by Das and Doniach within the context of the BMIT theory [28], which assumes the existence of non-superfluid liquid of Cooper pairs (Bose metal) in the zero-temperature limit. Previous to this, a scaling theory of the superconductor-insulator transition (SIT) has been devoloped by Fisher [35].…”

Origin of Nonlinear Transport across the Magnetically Induced Superconductor-Metal-Insulator Transition in Two Dimensions

“…The metallic resistance can be orders of magnitude smaller than the normal state resistance (ρ n ) implying that the metallic state exists as a separate phase rather than a point in the phase diagram. Despite many theoretical treatments [8,10,11,12,13,14,15,16,17], a consensus on the mechanism behind the metallic behavior is yet to be reached. Proposed origins of the metallic behavior include bosonic interactions in the nonsuperconducting phase [10,11], contribution of fermionic quasiparticles to the conduction [12,13], and quantum phase fluctuations [14,15].…”

“…Despite many theoretical treatments [8,10,11,12,13,14,15,16,17], a consensus on the mechanism behind the metallic behavior is yet to be reached. Proposed origins of the metallic behavior include bosonic interactions in the nonsuperconducting phase [10,11], contribution of fermionic quasiparticles to the conduction [12,13], and quantum phase fluctuations [14,15].In a recent paper [9] on the magnetically induced metallic behavior in Ta films, we have reported the nonlinear voltage-current (I-V ) characteristics that can be used to identify each phase. The superconducting phase is unique in having both a hysteretic I-V and an "immeasurably" small voltage response to currents below an apparent critical current I c .…”

Excitation spectrum of a two-dimensional long-range Bose liquid with supersymmetry

“…More exotic option is a "supersolid" ground state suggested long ago [1], which attracted a lot of attention recently [2]; this is a state which is expected to possess both superfluid and crystalline order simultaneously. Another direction of the search for unusual quantum ground states is related with a search for a "Bose-metal", that is, a bosonic analog of a Fermi-liquid, see for example [3,4]. Such a state would possess neither superfluid no crystalline order.…”