S. Takata et al., Nuclear magnetic resonance study on low-dimensional antiferromagnetic oxides: VOMoO4 and (V0.56Mo0.44)(2)O-5, J PHYS JPN, 70(4), 2001, pp. 1124-1127
We have carried out the nuclear magnetic resonance (NMR) of V-51 in VOMoO4,
which contains linear chains of distorted VO6 octahedra. The temperature d
ependence of the resonance shift K shows a small extremum around 100 K, tha
t can reasonably be compared with the Bonner-Fisher-type behavior of the su
sceptibility chi. V-51 relaxation rate T-1(-1), on the other hand, has a co
mplex temperature dependence: an exponential decrease down to similar to 10
0K, a near plateau between similar to 100 and similar to 34 K and a monoton
ous decrease below similar to 34 K. These are interpreted in terms of therm
al-excitations between split t(2g) orbitals in energy (DeltaE similar to 68
0 K) due to the local distortion of VO6 octahedra at high temperatures, one
-dimensional d-spin fluctuations, and a short-range magnetic ordering at lo
w temperatures, respectively. It is noted that the change in the a-axis len
gth must be taken into consideration to adequately describe the broad maxim
um observed in both K and X around 100 K. The V-51 NMR in the related oxide
(V0.56Mo0.44)(2)O-5 was also carried out, in which the VO6 and MoO6 octahe
dra form a planer network sharing the corner oxygen atoms.