Polarized Light‐Manipulated Magnetization of Organic Chiral Magnets

Abstract

have been fabricated, [9] implying that chiral materials with ferromagnetism can enhance the coupling between light and spin. In 2008, Train et al. designed and fabricated organic ferromagnetic materials [N(CH 3 )(n-C 3 H 7 ) 2 (s-C 4 H 9 )][MnCr(ox) 3 ], in which chirality shakes hands with magnetism with a T C of 7 K. [10] The magnetochiral dichroic effect can be enhanced by a factor of 17 when it enters into the ferromagnetic phase. In addition, organic ferromagnetism can be realized with specific molecular structures, [11] and some of them can be processed above the room-temperature Curie temperature. [12] Thus, it is possible to fabricate organic room-temperature ferromagnets with pronounced magneto-optic coupling effects, which can be used to enable a faster and less dissipative magnetic random access memory [13] and an all-optical manipulation of the magnetization in magnetooptical recording. [14] To date, self-assembly can build up organic charge-transfer networks with different dimensions to promote simultaneous dipoles and spin ordering, [15] such as ferromagnetic charge-transfer complexes tetrakis(dimethylamino)ethylene (TDAE):C 60 , [16] ferroelectric tetrathiafulvalene-p-bromanil (TTF:BA), [17] and magnetoelectric charge-transfer compound k-(ET) 2 Cu[N(CN) 2 ]Cl. [18] Thus, inspired by the progress of self-assembled organic charge-transfer networks, we attempted to screw organic crystals to a chiral helical structure and fabricate pure room-temperature organic chiral helical magnets without transition metal doping.In this work, we design and fabricate organic chiral chargetransfer magnets, for which chirality is characterized via both transmission electron microscopy (TEM) and a circular dichroism (CD) spectrometer. Ferromagnetism is studied with a superconducting quantum interference device. Organic chargetransfer magnets possess a high thermal stability and display a pronounced optomagnetic effect at room temperature. Importantly, linearly and circularly polarized lights with identical intensities are used to study polarized light-dependent magnetization and magnetoelectric coupling in chiral charge-transfer magnets.As shown in Figure 1a, a chiral poly(3-hexylthiophene-2,5-diyl) nanowire (nw-P3HT) is fabricated and characterized via TEM. To optimize the performance of the chirality, different concentrations of nw-P3HT ( Figure S1, Supporting Information) and N, N′-dipentyl-3,4,9,10-perylenedicarboximide (PTCDI; Figure S2, Supporting Information) are studied, as presented in the Supporting Information. Furthermore, the thermostability ( Figure S3, Supporting Information) and X-ray diffraction (XRD; Figure S4, Supporting Information) of chiral In this work, room-temperature organic chiral helical charge-transfer ferromagnets are fabricated with a high thermal stability. Compared with achiral ferromagnets, involving chirality-generated orbital angular momentum in chiral magnets will increase the value of magnetization. Under the stimulus of light, both right-handed and left-handed circularly polarized...

Organic magnetoelectric and optomagnetic couplings: perspectives for organic spin optoelectronics

“…Linear and circular indicate linear and circular polarization light excitation, respectively. Reproduced from Naaman and Waldeck 113 with permission from Annual Reviews, Inc., Wang et al 65 with permission from the American Physical Society and Gao et al 117 with permission from Wiley-VCH.…”

“…Compared to achiral organic ferromagnetic materials, the orbital angular momentum in chiral organic materials could be enhanced by the chirality 115,116 . The orbital angular momentum enhances the spin-photon coupling effect in organic chiral materials 65,117 . Qin et al combined chiral P3HT nanowires with C 60 to form chiral ferromagnetic P3HT:C 60 complexes, where both the ferromagnetism and magnetoelectric coupling effect could be tuned by polarized light.…”

Interfacial Engineering Enabled the Tunability of Organic Spin Polarization

“…In a specific study, the electronic states of copper/paramagnetic manganese can be altered to overcome the Stoner criterion, developing ferromagnetism at room temperature . Additionally, controlling the molecular configuration can further tune the magnetization strength. , While designing ferromagnetic materials, interfacial interactions could yield nonequilibrium crystal symmetries and substantial structural rearrangements on both sides of the interface. , Therefore, designing localized spin-ordered states at the donor–acceptor interface and fabricating organic hybrid interfaces with tunable magnetic properties are expected to open gateways for novel molecular spintronic devices.…”