Magnetic-field behavior of the spin-density-wave state in (TMTSF${)}_2$${\mathrm{AsF}}_6$

We report the 16.5 GHz microwave response of single crystal samples of (TMTSF${)}_2$${\mathrm{AsF}}_6$ at temperatures from 1.7–20 K as a function of external magnetic field. With the field applied along the hard (${\mathit{c}}^{\mathrm{*}}$) axis direction, striking changes are observed below ${\mathit{T}}_{\mathit{c}}$ in the microwave dielectric constant and conductivity, which are similar to (but more clear than) those reported in the ${\mathrm{PF}}_6$ salt. Following small changes in the low-temperature dielectric response, we are able to resolve the field dependence of the 3.5 and 1.9 K condensate phase boundaries. For the field applied along the chain direction, no changes are observed. Emphasis is placed upon the analysis of the H-T diagram (H∥${\mathit{c}}^{\mathrm{*}}$) and the series of subphases within the spin-density-wave manifold.