Magnetic properties of quasi-one-dimensional magnets AM3+ Si2O6 (A = Li, Na; M = Ti, V, Cr)

The magnetic properties of the quasi-one-dimensional magnet AM(3+)Si(2)O(6) (A = Li, Na; M = Ti, V, Cr) have been investigated in the light of the number of d-electron (spin number). The Ti(d(1))-compound shows a spin-Peierls like transition at the temperature higher than that (T-MAX) at the maximum point of the Bonner-Fisher curve, and the ground state is spin-singlet. The V(d(2)) - and Cr(d(3))-compounds do not show such transition and the ground states are long range antiferromagnetic ordered states. The T-MAX, where a short-range magnetic correlation within the chain is fully developed, decreases with increasing the M-M distance within the chain in the compounds with a fixed d(n). On the other hand, it decreases with increasing the number of d-electron in the Na-based compounds, although the M-M distance within the chain becomes shorter with increasing the number of d-electron. Any other factor such as the second nearest interaction or orbital degree of freedom should be taken into the consideration for the explanation of the T-MAX variation with the number of d-electron. (C) 2003 Elsevier B.V. All rights reserved.