Unconventional spin density wave in Bechgaard salt (TMTSF)2NO3

TL;DR

This paper investigates the anomalous low-temperature properties of TMTSF2NO3, revealing it exhibits an unconventional spin density wave state with gapless excitations, and proposes a new phase diagram for Bechgaard salts.

Contribution

The study provides evidence for an unconventional spin density wave in TMTSF2NO3, challenging the conventional SDW understanding and introducing a revised phase diagram for these salts.

Findings

TMTSF2NO3 exhibits gapless quasiparticle excitations.

Unconventional SDW explains angle-dependent magnetoresistance and Hall data.

Proposes a new phase diagram for Bechgaard salts.

Abstract

Among many Bechgaard salts, TMTSF2NO3 exhibits very anomalous low temperature properties. Unlike conventional spin density wave (SDW), TMTSF2NO3 undergoes the SDW transition at $\T_SDW\approx 9.5$ K and the low temperature quasiparticle excitations are gapless. Also, it is known that TMTSF2NO3 does not exhibit superconductivity even under pressure, while FISDW is found in TMTSF2NO3 only for P=8.5 kbar and B>20 T. Here we shall show that both the angle dependent magnetoresistance data and the nonlinear Hall resistance of TMTSF2NO3 at ambient pressure are interpreted satisfactory in terms of unconventional spin density wave (USDW). Based on these facts, we propose a new phase diagram for Bechgaards salts.