Spin polarization of excitons in organic multiferroic composites.

Shixuan Han,Shenqiang Ren,Shijie Xie,Wei Qin,Kun Gao,Liu Yang

doi:10.1038/srep28656

Abstract

Recently, the discovery of room temperature magnetoelectricity in organic charge transfer complexes has reignited interest in the multiferroic field. The solution processed, large-area and low cost organic semiconductor materials offer new possibilities for the functional all organic multiferroic devices. Here we report the spin polarization of excitons and charge transfer states in organic charge transfer composites by using extended Su-Schrieffer-Heeger model including Coulomb interaction and spin-flip effect. With the consideration of spin polarization, we suggest a possible mechanism for the origin of excited ferromagnetism.

Highlights

The discovery of room temperature magnetoelectricity in organic charge transfer complexes has reignited interest in the multiferroic field
With the consideration of spin polarization, we suggest a possible mechanism for the origin of excited ferromagnetism
We report a tight-binding model to study the spin polarization of excitons and charge transfer states in organic multiferroic charge transfer composites

Summary

OPEN Spin polarization of excitons in organic multiferroic composites

Shixuan Han[1], Liu Yang[1], Kun Gao[1], Shijie Xie[1], Wei Qin2,3 & Shenqiang Ren[2] received: 01 March 2016 accepted: 07 June 2016 Published: 23 June 2016. A few organic multiferroics with magnetoelectric coupling have been experimentally discovered[7,8,9,10,11] In this context, polymeric charge transfer crystals, consisting of polythiophene and fullerene, are shown external stimuli controlled magnetization which is resulted from the emergence of spin polarization through intra-molecular or inter-molecular excitons[11]. It is expected that an excited state should be spin polarized if the electron and hole are located in different segments of an organic donor-acceptor composite. Where j(j =D, A) is the molecule index, Hj describes the corresponding segment We model it in one-dimensional tight-binding approach15, 1School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Ji Nan, 250100, China.

Results and Discussion

Conclusions

Additional Information