The magnetic properties of the isotropic (J rail ≈ J rung), two-legged spin-ladder bis(2-amino-5-nitropyridinium) tetrabromocuprate monohydrate, [(5NAP) 2CuBr 4·H 2O], have been studied using a first-principles, bottom-up approach, which allows computation of macroscopic magnetic properties (for instance, the magnetic susceptibility) of a crystal from only a knowledge of its crystal packing. Evaluation of the J AB parameters, using the 163 K X-ray structure of [(5NAP) 2CuBr 4·H 2O], indicates that the magnetic topology of this crystal is a two-legged antiferromagnetic spin-ladder, with values of J rail and J rung of -22.2 cm -1 and -19.7 cm -1, respectively. These values are very close to those that best fit the experimental magnetic susceptibility curve, which are -13.59 cm -1 and -14.16 cm -1, respectively. Very weak diagonal interactions within each ladder [J(d3) = -0.9 cm -1] and between nearby ladders [J(d4) = -0.3 cm -1] are also found. The computed magnetic susceptibility curve obtained using the two-legged spin-ladder properly reproduces the experimental magnetic curve (a quantitative agreement is obtained by applying a linear scaling factor of about 0.75 to the energies). The singlet-triplet spin-gap of this spin-ladder was computed to be 17 K, in close agreement with the experimental result (11 K). The change of the spin-gap/J rail with the size (2xL) of the magnetic spin-ladder model space was found to converge towards 0.5, while that for a single-legged (1xL) spin-ladder converges towards zero, both in good agreement with the known trends for these systems. © Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
The mechanism of magnetic interaction in spin-ladder molecular magnets: A first-principles, bottom-up, theoretical study of the magnetism in the two-legged spin-ladder bis(2-amino-5-nitropyridinium) tetrabromocuprate monohydrate
Giorgi G.;
2005
Abstract
The magnetic properties of the isotropic (J rail ≈ J rung), two-legged spin-ladder bis(2-amino-5-nitropyridinium) tetrabromocuprate monohydrate, [(5NAP) 2CuBr 4·H 2O], have been studied using a first-principles, bottom-up approach, which allows computation of macroscopic magnetic properties (for instance, the magnetic susceptibility) of a crystal from only a knowledge of its crystal packing. Evaluation of the J AB parameters, using the 163 K X-ray structure of [(5NAP) 2CuBr 4·H 2O], indicates that the magnetic topology of this crystal is a two-legged antiferromagnetic spin-ladder, with values of J rail and J rung of -22.2 cm -1 and -19.7 cm -1, respectively. These values are very close to those that best fit the experimental magnetic susceptibility curve, which are -13.59 cm -1 and -14.16 cm -1, respectively. Very weak diagonal interactions within each ladder [J(d3) = -0.9 cm -1] and between nearby ladders [J(d4) = -0.3 cm -1] are also found. The computed magnetic susceptibility curve obtained using the two-legged spin-ladder properly reproduces the experimental magnetic curve (a quantitative agreement is obtained by applying a linear scaling factor of about 0.75 to the energies). The singlet-triplet spin-gap of this spin-ladder was computed to be 17 K, in close agreement with the experimental result (11 K). The change of the spin-gap/J rail with the size (2xL) of the magnetic spin-ladder model space was found to converge towards 0.5, while that for a single-legged (1xL) spin-ladder converges towards zero, both in good agreement with the known trends for these systems. © Wiley-VCH Verlag GmbH & Co. KGaA, 2005.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
