Quantized Hall conductance and its sign reversal in fieldinduced spindensity waves
Abstract
The signreversal phenomenon of the quantized Hall conductance as a function of an external magnetic field (H) observed in (TMTSF)_{2}X is investigated theoretically. After giving a general Hallconductance formula written in terms of order parameters of the fieldinduced spindensity wave (FISDW), we have done extensive meanfield calculations for a simplified standard model. It is shown that the many competing order parameters Δ_{n} (n=0,+/1,+/2, . . .) which coexist in a FISDW state can make the sign of the Hall constant change particularly near the subphase boundary of the FISDW and that numbering of the integer subphases (N=0,1,2, . . . stabilized in this order from high fields) does not necessarily coincide with the Hall number L defined by L=σ_{xy}/(e^{2}/h). We have found that the jumps of the Hall constant are accompanied by the spindensity wave gap closing when a FISDW is continuously evolving as H varies. In order for the sign reversal to occur a FISDW must contain many order parameters Δ_{n} with n being both signs.
 Publication:

Physical Review B
 Pub Date:
 July 1994
 DOI:
 10.1103/PhysRevB.50.921
 Bibcode:
 1994PhRvB..50..921M
 Keywords:

 73.40.Hm;
 74.70.Kn;
 75.30.Fv;
 Organic superconductors;
 Spindensity waves