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- Title
Magnetic Specific Heat of Anion-Radical Salt [Ni(bipy)<sub>3</sub>](TCNQ)<sub>4</sub>·(CH<sub>3</sub>)<sub>2</sub>CO at Very Low Temperatures.
- Authors
OLTÉSOVÁ, D.; ČIMÁR, E.; VASYLETS, G.; STARODUB, V.A.; FEHER, A.
- Abstract
Thermodynamic studies of the anion-radical salt system [Ni(bipy)3](TCNQ)4·(CH3)2CO, where TCNQ is 7,70,8,80-tetracyano-quinodimethane, are reported. The anion-radical salt systems based on TCNQ belong to a material class in which the arrangement of the anion-radical salt has considerable impact on the charge transfer and magnetic properties. The crystal structure of the studied compound consists of [Ni(bipy)3]2+ cations containing Ni2+ ions and four types of crystallographically independent anion-radicals TCNQ.- (A, B, C and D). These TCNQ.- radicals form two different types of TCNQ.- stacks (AABB and CCDD), where a strong exchange interaction is expected. The temperature dependence of the specific heat of a single crystal was studied in magnetic fields up to 5 T and in the temperature range from 0.4 K to 30 K. The temperature dependence of specific heat displays a broad Schottky-like maximum above 0.4 K. Using a single-ion approximation, the analysis of the temperature dependence of the specific heat below 10 K yields values for the anisotropy parameters, D=kB = -1:95 K and E=kB = 0:3 K. These results suggest that the observed maximum in the specific heat originates from Ni2+ ions while the exchange interaction between the transition metal ions and the TCNQ is negligible.
- Subjects
TETRACYANOQUINODIMETHANE; CHARGE transfer; EXCHANGE interactions (Magnetism); SINGLE crystals; TRANSITION metal ions
- Publication
Acta Physica Polonica: A, 2017, Vol 131, Issue 4, p925
- ISSN
0587-4246
- Publication type
Article
- DOI
10.12693/APhysPolA.131.925