Paramagnetic Susceptibility of Disordered N-Methyl-Phenazinium Tetracyanoquinodimethanide

The organic charge-transfer salt N-methyl-phenazinium tetracyanoquinodimethanide is described in terms of a one-dimensional disordered Hubbard model. For low temperatures and small transfer integrals this model reduces to a disordered Heisenberg anti-ferromagnet. The magnetic susceptibility of the latter can be described adequately by the disordered classical Heisenberg model. Fitting of susceptibility data by the one-dimensional classical Heisenberg model provides us with values of $t=0.055\mathrm{}$ eV, $U_{\mathrm{eff}}=0.130\mathrm{}$ eV, and $\sigma =0.136\mathrm{}$ eV for the parameters of the original Hubbard Hamiltonian.