⁷⁷Se NMR Evidence for the Development of Antiferromagnetic Spin Fluctuations of π-Electrons in λ-(BETS)₂GaCl₄

Multifunctional interplay among the conductivity, magnetism and dielectricity in π–d interacting λ-(BETS)2FeCl4

“…) It is noted that the band-structure calculations [28] give a peak of the staggered electronic susceptibility around q AF ¼ (0, p/c) that corresponds to the 2k F vector spanning two open Fermi surfaces. This is consistent with 77 Se-and 1 H NMR measurements on the superconducting GaCl 4 salt which reveal an existence of strong AFM spin fluctuations in its normal state [37,38], because the GaCl 4 salts can be iso-electronic to the FeCl 4 salt.…”

Evidence of antiferromagnetic fluctuation in the unconventional superconductor λ -(BETS) 2GaCl4 by CKobayashi1, Kawamoto2 2017Phys. Rev. B265260View full textAdd to dashboardCite

“…An increase in 1/T 1 T was observed below 25 K in 1 H NMR [11], but the 77 Se NMR experiment suggested that 1/T 1 T is constant or weak temperature dependent below 70 K [12,13]. Moreover, the linewidths of 77 Se NMR using randomly oriented samples and single-crystal samples show the different behaviors at low temperatures [12,13]. The contradictions arise from experimental difficulties with low sensitivity and broad linewidths in the 77 Se NMR signal and the additional relaxation mechanism from molecular motions due to weak coupling of the 1 H nuclei with the π conducting electrons.…”

“…1 H and 77 Se NMR measurements have been performed previously, but several results appear contradictory. An increase in 1/T 1 T was observed below 25 K in 1 H NMR [11], but the 77 Se NMR experiment suggested that 1/T 1 T is constant or weak temperature dependent below 70 K [12,13]. Moreover, the linewidths of 77 Se NMR using randomly oriented samples and single-crystal samples show the different behaviors at low temperatures [12,13].…”

Field-Induced Superconductors: NMR Studies of λ–(BETS)2FeCl4

“…Kiso(ax) is a constant determined by the isotropic (axial) hyperfine field produced by the 4p π spin polarization of the BETS Se π-electrons [26].…”