Charge Order Breaks Magnetic Symmetry in Molecular Quantum Spin Chains

Table 1

Transition temperatures for charge localization 𝑇_𝜌, charge-order 𝑇_CO, spin-Peierls transition 𝑇_SP and Néel order 𝑇_𝑁 of different (TMTTF)₂𝑋 salts. 𝐽 denotes the antiferromagnetic exchange constant obtained from susceptibility measurements fitted according to [8], 2𝛿 is the charge imbalance between two TMTTF molecules (for 𝑇→0) measured by vibrational spectroscopy and Δ_CO indicate the zero-temperature charge gap derived from dc transport along the 𝑎-direction. 𝜙 is the angle the g-tensor rotates around the molecular axis in the CO state determined at 𝑇≈𝑇_CO/2.

Compound	𝑇𝜌	𝑇CO	𝑇SP	𝑇𝑁	𝐽	2𝛿	ΔCO	𝜙
	(K)	(K)	(K)	(K)	(K)	(e)	(K)	(^∘)
(TMTTF)2PF6	250	67	19	—	420	0.15	small	22
(TMTTF)2AsF6	250	102	13	—	410	0.21	310	22
(TMTTF)2SbF6	240	157	—	8	400	0.29	745	32