Nonequilibrium persistent currents in charge-density-wave systems

Harrison, N.

doi:10.1103/physrevb.66.121101

Cited by 16 publications

(18 citation statements)

References 22 publications

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“…Elastic energy considerations (see Appendix) show that the region in which |F| > |F p | propagates inwards from the sample surface as the magnetic field changes, so that the volume-fraction of the sample able to contribute to the diamagnetic screening decreases. This is analogous to the scenario in the Bean model of type-II superconductors [29,40,41], yielding, under the approximation of a cylindrical sample, an irreversible susceptibility…”

Section: Magnetic Torque Measurementsmentioning

confidence: 65%

“…On sweeping the field down for the first time, the magnetization rises to meet the path which will be followed by subsequent downsweeps. Moreover, it proves to be impossible to go back to the encircled value of M by merely changing the field; data recorded on subsequent upsweeps fall below it, [29]). Estimates of the coercion field H * (x-symbols) are also shown.…”

Section: Magnetic Torque Measurementsmentioning

confidence: 99%

“…17 reproduces the experimental result indicates that the volume fraction of the sample f (∆H) that is able to respond with an irreversible susceptibility ∆χ 0 declines in a simple quadratic manner with ∆H (see Eq. 16), behaviour typical of critical-state models such as that of Bean [29,40,41]; here, f (∆H) is the cross-sectional area of the remaining non-critical portion of the sample. As the magnetization varies throughout the sample, Maxwell's relation j mag = ∇ × M [28] implies that a magnetic-field-induced critical state always involves currents.…”

Section: Magnetic Torque Measurementsmentioning

confidence: 99%

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Unconventional quantum fluid at high magnetic fields in the marginal charge-density-wave systemα−(BEDT−TTF)2MHg(

et al. 2004

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Single crystals of the organic charge-transfer salts α-(BEDT-TTF)2M Hg(SCN)4 have been studied using Hall-potential measurements (M =K) and magnetization experiments (M = K, Rb). The data show that two types of screening currents occur within the high-field, low-temperature CDWx phases of these salts in response to time-dependent magnetic fields. The first, which gives rise to the induced Hall potential, is a free current (j free ), present at the surface of the sample. The time constant for the decay of these currents is much longer than that expected from the sample resistivity. The second component of the current appears to be magnetic (jmag), in that it is a microscopic, quasi-orbital effect; it is evenly distributed within the bulk of the sample upon saturation. To explain these data, we propose a simple model invoking a new type of quantum fluid comprising a CDW coexisting with a two-dimensional Fermi-surface pocket which describes the two types of current. The model and data are able to account for the body of previous experimental data which had generated apparently contradictory interpretations in terms of the quantum Hall effect or superconductivity.

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Section: Magnetic Torque Measurementsmentioning

confidence: 65%

Section: Magnetic Torque Measurementsmentioning

confidence: 99%

Section: Magnetic Torque Measurementsmentioning

confidence: 99%

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Unconventional quantum fluid at high magnetic fields in the marginal charge-density-wave systemα−(BEDT−TTF)2MHg(

et al. 2004

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“…A critical state nevertheless develops, yielding magnetic hysteresis that can be observed experimentally within orbitally quantized DW states. The existence of such a critical state has been directly demonstrated in charge-transfer salts of the composition α-(BEDT-TTF) 2 M Hg(SCN) 2 (where M = K and Rb) [6,9,17,18]. Figure 3a-c show examples in α-(BEDT-TTF) 2 KHg(SCN) 2 .…”

Section: Critical Statementioning

confidence: 91%

Orbitally Quantized Density-Wave States Perturbed from Equilibrium

Harrison

McDonald

Singleton

2008

The Physics of Organic Superconductors and Conductors

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We consider the effect that a change in the magnetic induction B has in causing an orbitally quantized field-induced spin-or charge density wave (FISDW or FICDW) state to depart from thermodynamic equilibrium. The competition between elastic forces of the density wave (DW) and pinning leads to the realization of a critical state that is in many ways analogous to that realized within the vortex state of type II superconductors. Such a critical state has been verified experimentally in charge-transfer salts of the composition α-(BEDT-TTF)2M Hg(SCN)4, but should be a generic property of all orbitally quantized DW phases. The metastable state consists of a balance between the DW pinning force and the Lorentz force on extended currents associated with drifting cyclotron orbits, resulting in the establishment of persistent currents throughout the bulk and to the possibly of a three-dimensional 'chiral metal' that extends deep into the interior of a crystal.

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“…This same non-equilibrium distribution also puts the CDW under considerable tension or compression, rather like a spring. Orbital quantization of the 2D pocket enables the magnetic field to be directly coupled to this "spring" via the variation of the chemical potential [21,32]. The magnetic field therefore provides a means to drive the compression and tension of the CDW and subsequent development of non-equilibrium persistent currents [21,32].…”

Section: Introductionmentioning

confidence: 99%

Recent high-magnetic-field studies of unusual groundstates in quasi-two-dimensional crystalline organic metals and superconductors

Singleton

Harrison

McDonald

et al. 2006

Journal of Physics and Chemistry of Solids

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After a brief introduction to crystalline organic superconductors and metals, we shall describe two recently-observed exotic phases that occur only in high magnetic fields. The first involves measurements of the non-linear electrical resistance of single crystals of the charge-density-wave (CDW) system (Per) 2 Au(mnt) 2 in static magnetic fields of up to 45 T and temperatures as low as 25 mK. The presence of a fully gapped CDW state with typical CDW electrodynamics at fields higher that the Pauli paramagnetic limit of 34 T suggests the existence of a modulated CDW phase analogous to the Fulde-Ferrell-Larkin-Ovchinnikov state. Secondly, measurements of the Hall potential of single crystals of α-(BEDT-TTF) 2 KHg(SCN) 4 , made using a variant of the Corbino geometry in quasistatic magnetic fields, show persistent current effects that are similar to those observed in conventional superconductors. The longevity of the currents, large Hall angle, flux quantization and confinement of the reactive component of the Hall potential to the edge of the sample are all consistent with the realization of a new state of matter in CDW systems with significant orbital quantization effects in strong magnetic fields.

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Nonequilibrium persistent currents in charge-density-wave systems

Cited by 16 publications

References 22 publications

Unconventional quantum fluid at high magnetic fields in the marginal charge-density-wave systemα−(BEDT−TTF)2MHg(

Unconventional quantum fluid at high magnetic fields in the marginal charge-density-wave systemα−(BEDT−TTF)2MHg(

Orbitally Quantized Density-Wave States Perturbed from Equilibrium

Recent high-magnetic-field studies of unusual groundstates in quasi-two-dimensional crystalline organic metals and superconductors

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