Quantum oscillations in quasi-one-dimensional metals with spin-density-wave ground states

Abstract

We consider the magnetoresistance oscillation phenomena in the Bechgaard salts $(\mathrm{TMTSF}{)}_{2}X,$ where $X={\mathrm{ClO}}_{4},$ ${\mathrm{PF}}_{6},$ and ${\mathrm{AsF}}_{6}$ in pulsed magnetic fields to 51 T. Of particular importance is the observation of a new magnetoresistance oscillation for $X={\mathrm{ClO}}_{4}$ in its quenched state. In the absence of any Fermi-surface reconstruction due to anion order at low temperatures, all three materials exhibit nonmonotonic temperature dependence of the oscillation amplitude in the spin-density-wave (SDW) state. We discuss a model where, below a characteristic temperature ${T}^{*}$ within the SDW state, a magnetic breakdown gap opens.