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

Abstract

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.

Phase diagram and structure of the charge-density-wave state in a high magnetic field in quasi-one-dimensional materials: A mean-field approach

“…Our results are aimed to help analyze the rather complicated phase diagram of the CDW state in the high magnetic field observed in a number of organic metals, [26][27][28][29][30][31][32][33][34] such as ␣-͑BEDT-TTF͒ 2 KHg͑SCN͒ 4 ͑see discussion in Ref. 45͒, ͑Per͒ 2 M͑mnt͒ 2 ͑M being Au, Pt, Cu͒, [35][36][37][38][39] etc., where the transition from CDW 0 to the high-field CDW x phase is within the experimentally achievable magnetic fields.…”

“…[26][27][28][29][30][31][32][33][34][35][36][37][38] In the present paper, we study the CDW phase diagram and the properties of the CDW state at finite temperature below the transition point in the mean-field approximation. This study links the results of susceptibility calculations and the results from the soliton approach.…”

Paramagnetic effect of magnetic field on superconductors with charge-density waves

“…Nevertheless, it always manifests itself in CDW metals or insulators and can even modify the very CDW wave vector [21][22][23][24][25]. Therefore, in calculating the total response both the paramagnetic (spin) and diamagnetic contributions should be taken into account [18,[26][27][28][29][30][31][32][33].…”

Magnetic quantum oscillations in the charge-density-wave state of the organic metals α-(BEDT-TTF)2MHg(SCN)4 with M = K and Tl

“…Most of these experiments were focused on the high-field state, above the kink field B k . Consequently, all the proposed explanations, involving various exotic phenomena such as bulk quantum Hall effect [56,59], Froehlich superconductivity [28], or an unconventional quantum liquid [32], associated …”

“…However, a number of anomalies are still a matter of debate. One of the problems in this respect is that there is no general consensus as to the exact topology of the reconstructed Fermi surface in the CDW state [25,[31][32][33].…”