Origin of the split quantum oscillation wave form inα−(BEDT−TTF)2KHg(SCN

Abstract

We report the results of a detailed study of the field orientation dependence of the de Haas-van Alphen wave form in ␣-(BEDT-TTF) 2 KHg(SCN) 4 over a wide range of angles and fields. By considering the field orientation dependence of the sign and phase of the fundamental ␣ frequency, at fields both well above and below the kink transition field, it is found that the product of the effective mass with the electron g factor is approximately constant. This implies that spin splitting cannot occur within the low-magnetic-field phase until the angle between the magnetic field and the normal to the conducting planes is ϳ42°. This finding contrasts greatly with that recently published by Sasaki and Fukase. The results of the present study imply that the electron-electron interactions are largely field independent in this material, while a field dependence of the electron-phonon interactions is still tenable. The manner in which the amplitude of the wave form of the oscillations is damped within the low-magnetic-field phase is suggestive of a nonharmonically indexed reduction of the amplitude, thereby eliminating explanations in terms of magnetic breakdown or impurity scattering. Meanwhile, the presence of a large amplitude second harmonic within the low-magnetic-field phase that has a negative sign over a broad range of angles can be explained only by the frequency doubling effect.

Magnetic-field-induced dimensional crossover in the organic metalα-(BEDT-TTF)2KHg(SCN)4

“…The spin reduction factor R S can be evaluated from spin-zeros experiments. So far, such experiments have been done for α-(BEDT-TTF) 2 KHg(SCN) 4 only at ambient pressure, (at high magnetic fields, where the CDW gap is strongly suppressed), yielding 43,44 gm * = 3.65 ± 0.02. Making a correction to the pressure-dependent effective mass, which changes from m * ≈ 2.0 at ambient pressure to 1.3 at 6 kbar, and assuming a pressure-independent g-factor we substitute gm * = 2.37 in the spin reduction factor to obtain a rough estimate R S (1) ≃ 0.8 and R S (2) ≃ 0.4.…”

Field-induced charge-density-wave transitions in the organic metal α-(BEDT-TTF)2KHg(SCN)4 under pressure

“…Moreover, it is known, that there is an anomalously strong second harmonic signal at 2F α as well as additional SdH frequencies at F λ = 170 T and F ν = F α + F λ , which only appear in the CDW state. The origin of these multiple frequencies is obviously related to the complex magnetic-breakdown network, although their detailed description is somewhat controversial [28,29,[31][32][33]. Under pressure, the magnitude of the magnetoresistance in Fig.…”

Nonequilibrium persistent currents in charge-density-wave systems

“…I begin my comparison by considering the irreversible susceptibility. On computing χ irr , using Equation (5) and the established parameters (F ≈ 670 T, m * ≈ 2 m e , N 2D ≈ 1.6 × 10 26 m −3 , g 1D ≈ g 2D and τ ≈ 2 ps [25] for α-(BEDT-TTF) 2 KHg(SCN) 4 ), the model estimates (χ mod ) listed in Table I are found to agree rather well with the experimental values (χ exp ) [14] both at half-integral and integral filling factors.…”