Does the “quantized nesting model” properly describe the magnetic-field-induced spin-density-wave transitions?

Abstract

Theoretical reinvestigation of a so-called field-induced spin-density-wave (FISDW) phase diagram in a magnetic field in quasi-one-dimensional compounds (TMTSF)2X (X=PF6, ClO4, AsF6, etc.) has revealed some novel qualitative features. Among them are (1) the FISDW wave vector is never strictly quantized; and (2) the FISDW phase diagram consists of two regions: (a) “Quantum FISDW,” where there exist jumps of the FISDW wave vectors between different FISDW subphases and (b) “Quasiclassical FISDW,” where the jumps disappear above some critical points and only one FISDW phase (characterized by a wave vector oscillating with a magnetic field) exists. Both these features are due to taking account of the breaking of an electron-hole symmetry. They contradict the previous textbook theoretical results (including the calculations of the “Three Dimensional Quantum Hall Effect”) performed by means of the “Quantized Nesting Model” which explicitly assumes the existence of the electron-hole symmetry. We stress that some effects related to the phenomena described above were experimentally observed but not properly interpreted.