2025/10/31 by Aizawa, Hirohito
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2510.27115
We have theoretically investigated the magnetic properties of the quasi-two-dimensional organic conductor λ-(BETS)2GaCl4 using a multi-band Hubbard model and the two-particle self-consistent method. We have employed a four-band model, where each BETS molecule is considered as a site, and a two-band model, treating each BETS dimer as a site. Our results for the temperature dependence of the Stoner factor reveal a kink around Tkink ≈ 5 meV, indicating a change in the dominant magnetic fluctuations. Above Tkink, it shows a broad structure indicating smeared antiferromagnetic (AFM) fluctuations, while below Tkink, the spin susceptibility peaks at a wavevector corresponding to spin-density-wave (SDW)-like fluctuations. As the intra-dimer transfer integral increases, the kink disappears, and the AFM fluctuations are enhanced. Our findings are consistent with experimental observations, which also report a change in magnetic properties from AFM to SDW-like fluctuations upon cooling.