A new quantum fluid at high magnetic fields in the marginal charge-density-wave system $\alpha$-(BEDT-TTF)${}_{2}M$Hg(SCN)${}_4$ (where $M=$~K and Rb)

Abstract

Single crystals of the organic charge-transfer salts $\alpha$-(BEDT-TTF)${}_{2}M$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 CDW${}_x$ 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 (${\mathbf{j}}_{\mathrm{free}}$), 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 (${\mathbf{j}}_{\mathrm{mag}}$), 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.

13 pages, 11 figures

References in corpus (6)

• Chiral Surface States in the Bulk Quantum Hall Effect
• Phase Diagram for Charge Density Waves in a Magnetic Field
• Orbital effect of a magnetic field on the low temperature state in the organic metal $\alpha$-(BEDT-TTF)${}_2$KHg(SCN)${}_4$
• Magnetic field - temperature phase diagram of the organic conductor alpha-(BEDT-TTF)2KHg(SCN)4
• Critical State Behaviour in a Low Dimensional Metal Induced by Strong Magnetic Fields
• Persistent Currents in Charge-density Wave Systems

Cited by in corpus (4)

• Unusual high-field metal in a Kondo insulator
• Superconductivity in the charge-density-wave state of the organic metal α-(BEDT-TTF)2KHg(SCN)4
• Magnetic quantum oscillations in the charge-density-wave state of the organic metals $\alpha$-(BEDT-TTF)${}_2$MHg(SCN)${}_4$ with M = K and Tl
• Recent high-magnetic-field studies of unusual groundstates in quasi-two-dimensional crystalline organic metals and superconductors