2024/09/13 by Marvin Schmidt, Schmidt, Marvin, Savita Priya +9
Materials Science · #FOS: Physical sciences #Magnetism in coordination complexes #Organic and Molecular Conductors Research #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.2409.08656
openalex publication_date 2024/09/13 · openalex created_date 2024/10/23 · openalex updated_date 2026/07/28
The two-dimensional molecular conductor κ-(BETS)2Mn[N(CN)2]3 undergoes a sharp metal-to-insulator phase transition at T\rm MI≈ 21 K, which has been under scrutiny for many years. We have performed comprehensive infrared investigations along the three crystallographic directions as a function of temperature down to 10 K, complemented by electron spin resonance and dc-transport studies. The in-plane anisotropy of the optical conductivity is more pronounced than in any other κ-type BEDT-TTF or related compounds. The metal-insulator transitions affects the molecular vibrations due to the coupling to the electronic system; in addition we observe a clear splitting of the charge-sensitive vibrational modes below T\rm MI that evidences the presence of two distinct BETS dimers in this compound. The Mn[N(CN)2]3- layers are determined by the chain structure of the anions resulting in a rather anisotropic behavior and remarkable temperature dependence of the vibronic features. At low temperatures the ESR properties are affected by the Mn2+ ions via π-d-coupling and antiferromagnetic ordering within the π-spins: The g-factor shifts enormously with a pronounced in-plane anisotropy that flips as the temperature decreases; the lines broaden significantly; and the spin susceptibility increases upon cooling with a kink at the phase transition.