Electron-lattice coupling and the broken symmetries of the molecular salt (TMTTF)$_2$SbF$_6$

TL;DR

This study investigates how pressure influences phase transitions in (TMTTF)$_2$SbF$_6$, revealing the suppression of charge order and antiferromagnetism, and highlighting the role of electron-lattice coupling in the material's evolution.

Contribution

It provides a comprehensive phase diagram for (TMTTF)$_2$SbF$_6$ and emphasizes the significance of electron-lattice interactions in pressure-induced phase changes.

Findings

Charge ordering is suppressed above 0.5 GPa.

Antiferromagnetic order disappears with pressure.

Ground state becomes a singlet at high pressure.

Abstract

(TMTTF)$_2$SbF$_6$ is known to undergo a charge ordering (CO) phase transition at $T_{CO}\approx156K$ and another transition to an antiferromagnetic (AF) state at $T_N\approx 8K$. Applied pressure $P$ causes a decrease in both $T_{CO}$ and $T_N$. When $P>0.5 GPa$, the CO is largely supressed, and there is no remaining signature of AF order. Instead, the ground state is a singlet. In addition to establishing an expanded, general phase diagram for the physics of TMTTF salts, we establish the role of electron-lattice coupling in determining how the system evolves with pressure.