Spin dimerization in a mixed-valent dodecylamine-intercalated vanadium oxide system

Electron spin resonance study of room-temperature ferromagnetism in vanadium oxide nanosheets prepared by room-temperature synthesis

“…The magnetic field dependence of the magnetization, displaying a low-field region in contrast to the wide magnetic field plot in the previous work [13], measured at 5 K and 300 K (Fig. 2) manifests ferromagnetic (FM) hystereses, with a remanent magnetization of w5.6 Â 10 À5 m B /V at 300 K, and with a coercive field of w17 mT at 5 K and w4.7 mT at 300 K. The small magnetization, just order of w10 À4 m B /V, suggests that most spins are antiferromagnetically correlated.…”

“…A dodecylamine-intercalated vanadium oxide (C12VO) sample, used also in our recent work [13], was obtained by adding V 2 O 5 powder (Sigma) and dodecylamine (Aldrich, 98%) to ethanol in a molar ratio of 2:1 and stirring for 2 h in air [14e16]. The resulting yellow solution adduct was hydrolyzed with deionized water and stirred for 48 h at room temperature, the amount of ethanol/water being controlled at 6.5/8.75 (ml).…”

“…As-grown V 2 O 5 (C n H 2n þ 1 NH 3 ) 2 (H 2 O) 2 showed no electron spin resonance (ESR) signal [11], while hydrothermally synthesized (H 3 N(CH 2 ) 3 NH 3 )[V 4 O 10 ], with V 4þ / V 5þ w 1, is known to be a spin-1/2 dimer system [12]. In our recent work, an abrupt spin dimerization with nonmagnetic impurityinduced antiferromagnetism has been reported in the mixed-valent dodecylamine-intercalated vanadium oxide [13]. It is shown that the sample in that work, used also in the current work, in fact is composed of nanosheets, displaying room-temperature ferromagnetism coexisting with AFM spins.…”