Figure 6: Magnetic properties as a function of C18(OH)yFx stoichiometry.
From: Room temperature organic magnets derived from sp3 functionalized graphene
(a) The mean magnetization map indicates which C18(OH)yFx (x=0–8, y=0–8) stoichiometries are likely to exist in ferromagnetic and non-magnetic ground states. Both –F and –OH groups are assumed to be randomly distributed across the sample (as suggested by STEM–HAADF elemental mapping, cf. Fig. 3) at zero temperature and the possibility of kinetically controlled –F/–OH migration is not considered. The white circles indicate experimentally studied samples: 1—C18(OH)1.8F7.2 (ferromagnetic in the ground state), 2—C18(OH)1.5F6 (ferromagnetic in the ground state), 3—C18(OH)2F3 (diamagnetic in the ground state), 4—C18(OH)2.6F4.7 (ferromagnetic in the ground state), 5—C18(OH)2.4F7 (ferromagnetic in the ground state), 6—C18F2.5 (diamagnetic in the ground state), 7—C18F4 (ferromagnetic in the ground state) and 8—C18F6.3 (diamagnetic in the ground state). (b) The isothermal magnetization (M) curve of C18(OH)1.8F7.2 (Sample No. 1) as a function of an external magnetic field (H), recorded at a temperature of 5 K. (c) M versus H curve of C18(OH)1.5F6 (Sample No. 2), recorded at a temperature of 5 K. (d) M versus H curve of C18(OH)2F3 (Sample No. 3), recorded at a temperature of 5 K. (e) M versus H curve of C18(OH)2.6F4.7 (Sample No. 4), recorded at a temperature of 5 K. (f) M versus H curve of C18(OH)2.4F7 (Sample No. 5), recorded at a temperature of 5 K. (g) M versus H curve of C18F2.5 (Sample No. 6), recorded at a temperature of 5 K. (h) M versus H curve of C18F4 (Sample No. 7), recorded at a temperature of 5 K. (i) M versus H curve of C18F6.3 (Sample No. 8), recorded at a temperature of 5 K. The insets in panel (b,c,e,f and h) show the behaviour of the respective hysteresis loops around the origin with the saturation magnetization (MS) indicated.
