Large magnetic-field-induced Fermi surface changes in alpha -ET₂KHg(NCS)₄

Abstract

We repon angle-dependent magnetoresistance experiments on the charge-transfer salt cr-ET2KHgW.S)r using fields of up to 30 T. The data indicale tJnI the widely reported high-field 'kink' observed in the magnetoresistance of Ute a-ET$Wig(NCS)4 (M = K, TI, Rb) family of charge-bansfer salts represents a transition from an imperfectly nested spin-density wave gmund state, characterired by a quasi-onedimensional Fermi surface sheet tilted with re~peet to Ihe b'c plane, to a state with a cylindrical two-dimensional Fermi surface. Charge-transfer salts of the molecule ET (bis(ethy1enedithio)tetrathiafulvalene or BEDT

Unconventional Charge-Density Wave in the Organic Conductorα−(BEDT−TT<

“…(7) with the experimentally observed behavior of -BEDT-TTF 2 KHgSCN 4 , we have measured the interlayer resistance of a single crystal of this compound as a function of temperature, magnetic field strength, and orientation. The measurements were performed, using the standard four-probe ac technique (f 330 Hz, I sample 10 A) in the temperature interval 1.4 -20 K under magnetic field up to 15 T. The obtained ADMR data are consistent with the previous reports [18][19][20].…”

“…Here is the angle the projected magnetic field on the a-c plane makes with the c axis. The origin of this surprising ADMR has been discussed earlier [17][18][19][20][21][22], but only partial answers were found. These earlier models cannot describe the broad peak in the resistance around 0 (see Figs.…”

Spin-charge separation in molecular wire conductance simulations

“…In general, it was discovered that the spindensity waves are more localized than the charge-density waves. 80,81 While the initial studies examined systems with only spin-density waves or charge-density waves, recent theoretical 89 and experimental [90][91][92][93][94][95] studies have demonstrated both types in coexistence.…”

Theory of Coexisting Charge and Spin-Density Waves in (TMTTF)2Br, (TMTSF)2PF6 and α-(BEDT-TTF)2MHg(SCN)4

“…In (TMTTF) 2 Br, the experiment finds signatures of even a 4k F lattice displacive instability (k F = Fermi wavevector), along with the more usual 2k F charge instability within the SDW phase [3,4]. The status of the experiments in (BEDT-TTF) 2 MHg(SCN) 4 is very similar: while early magnetic susceptibility [12] and µsr [13] measurements provided clear evidence for a SDW, measurement of angledependent magnetoresistance oscillations [5,6,7,8] have engendered the view that the insulating phase here is a "mysterious" state that is a "SDW accompanied by CDW" or a "CDW accompanied by SDW" [12] . The authors of a recent 13 C-NMR study have concluded that the insulating state here is not a SDW at all, but is a CDW [9].…”

“…The SC-SDW proximity then suggests that it is crucial to understand the precise nature of the SDW and the mechanism of its formation, as well as the roles played by dimensionality effects and strong Coulomb interactions [1,2]. Very recent experiments on several materials indicate that the SDWs in the organics are highly unconventional in nature [3,4,5,6,7,8,9], imposing strict requirements of any theory of the SDWs.…”