Magnetic properties of very-high-spin organic π-conjugated polymers based on Green’s function theory

Abstract

Magnetic properties of two very-high-spin organic pi-conjugated polymers have been investigated theoretically by means of the many-body Green's function method with random phase approximation. The polymers are designed with a large density of cross-links and alternating connectivity of radical modules with unequal spin quantum numbers (S), macrocyclic S=2 or 3, and cross-linking S=1/2 modules, which permit large net S values for either antiferromagnetic or ferromagnetic exchange coupling between the modules. The numerical results reveal that, ascribing to the zero-temperature spin fluctuations, the sublattice magnetizations of the two polymers are both smaller than their classical spin values and the ground-state magnetizations of them are also smaller than their predicted values in the antiferromagnetic exchange coupling case. However, these magnetic behaviors do not occur in the ferromagnetic exchange coupling case. On the basis of our synthesis of the temperature dependence of the magnetic susceptibility multiplied by temperature, and through comparing the theoretical results with the experimental measurements, it is concluded that the magnetic exchange couplings between the modules within the two high-spin polymers should be ferromagnetic exchange couplings, which are consistent with other theoretical results drawn from the investigations into the ground-state properties of the two organic polymers.

Influence of DCM dye doping on the magnetic field dependent electroluminescence in organic light emitting diodes

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“…Several possible models have been proposed to explain these MFEs, such as Bipolaron mechanism [8], exciton-charge reaction mechanism [9], triplet-triplet annihilation process (TTA S*) → [10] and magnetic field modulated hyperfine interaction [11]. Relevant work has been carried out by several groups [11][12][13][14][15][16][17][18][19][20][21]. In our latest study on the MFEs in pure Alq 3 based OLEDs [22], we found that the MEL shows a sharp increase at low fields and followed by a significant decrease at high fields more than about 40 mT at low temperature (T≤150 K) and large injection current.…”

Strain-induced spin-gapless semiconductors and pure thermal spin-current in magnetic black arsenic-phosphorus monolayers

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Current-induced enhancement of DNA bubble creation

“…, ; e d t t i [47,48] (6), the average force on the n-th GC pair depends on the electron population, changing with the applied bias.…”