home | Authors | Referees | Browse | Announcement | Download | Subscription | Contact us | CPS Journals | Chinese Dear authors, Thank you very much for your contribution to Chinese Physics B. Your paper has been published in Chinese Physics B, 2014, Vol.23, No.5. Attached is the PDF offprint of your published article, which will be convenient and helpful for your communication with peers and coworkers. Readers can download your published article through our website http://www.iop.org/cpb or http://cpb.iphy.ac.cn What follows is a list of related articles published recently in Chinese Physics B. The basis of organic spintronics：Fabrication of organic spin valves Chen Bin-Bin, Jiang Sheng-Wei, Ding Hai-Feng, Jiang Zheng-Sheng, Wu Di Chin. Phys. B . 2014, 23(1): 018104. Full Text: PDF (757KB) Recent progress in perpendicularly magnetized Mn-based binary alloy films Zhu Li-Jun, Nie Shuai-Hua, Zhao Jian-Hua Chin. Phys. B . 2013, 22(11): 118505. Full Text: PDF (3135KB) Oxide magnetic semiconductors：Materials, properties, and devices Tian Yu-Feng, Hu Shu-Jun, Yan Shi-Shen, Mei Liang-Mo Chin. Phys. B . 2013, 22(8): 088505. Full Text: PDF (1219KB) The effect of dimerization on the magnetoresistance in organic spin valves Wang Hui, Hu Gui-Chao, Ren Jun-Feng Chin. Phys. B . 2013, 22(5): 058504. Full Text: PDF (539KB) Reactively sputtered Fe3O4-based films for spintronics Li Peng, Jin Chao, Mi Wen-Bo, Bai Hai-Li Chin. Phys. B . 2013, 22(4): 047505. Full Text: PDF (2911KB) The effects of electric and magnetic fields on the current spin polarization and magnetoresistance in a ferromagnetic/organic semiconductor/ferromagnetic (FM/OSC/FM) system Wang Yu-Mei, Ren Jun-Feng, Yuan Xiao-Bo, Dou Zhao-Tao, Hu Gui-Chao Chin. Phys. B . 2012, 21(10): 108508. Full Text: PDF (260KB) ----------------------------------------------------------------------------------------------------- Chin. Phys. B Vol. 23, No. 5 (2014) 058106 TOPICAL REVIEW — Magnetism, magnetic materials, and interdisciplinary research Progress in organic spintronics∗ Yang Fu-Jiang(杨福江), Han Shi-Xuan(韩士轩), and Xie Shi-Jie(解士杰)† School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China (Received 28 February 2014; published online 25 March 2014) Recent progress in organic spintronics is given an informative overview, covering spin injection, detection, and trans- port in organic spin valve devices, and the magnetic field effect in organic semiconductors (OSCs). In particular, we focus on our own recent work in spin injection and the organic magnetic field effect (OMFE). Keywords: organic material, spintronics, spin injection, organic magnetic field effect PACS: 81.05.Lg, 85.75.–d, 75.47.–m DOI: 10.1088/1674-1056/23/5/058106 1. Introduction processed at room temperature. It is well known that In recent years, the field of organic spintronics has seen organic small molecules and polymers have many inter- great progress, both experiment and theory. The increased mo- esting electronic, magnetic, and optical properties. Or- ganic light-emitting diodes (OLEDs) for flat-screen TVs, cell tivation comes from the unique advantages of organic semi- phone displays, billboards, and computer displays have been conductors, including flexibility, low weight, and low-cost fab- fabricated.[7–9] In addition, OSCs have extremely weak spin– rication, as well as from the strong technical support recently orbit coupling and weak hyperfine interaction, so the electron emerging in the fields of chemistry and material science. spin diffusion length is especially long.[3] These properties As the enabling carrier for message storage and trans- make them ideal for spin-polarized injection and transport ap- port, an electron has two aspects: charge and spin. In nor- plications, which are anticipated to be the next hot topic in mal electronic devices, they are used separately. For exam- spintronics. Organic spintronics not only broadens our under- ple, integrated circuit devices carry messages based on the standing of the physical world of organic materials but also has electronic charges, while diskettes store messages based on a substantial impact on spintronic and bionomic applications. the electronic spins. However, the discovery of giant magne- A comprehensive review of organic spintronics, addressing toresistance (GMR) and tunneling magnetoresistance (TMR) both theoretical and experimental aspects, appeared in 2007, in metallic spin valves has revolutionized applications such which covered the major results published up to that date.[10] as magnetic recording and memory, and has launched a new A later article reviewed the major experimental results.[11] In field of spin electronics — spintronics[1–3] — which is cen- addition, a brief overview of the first eight years of spin trans- tered on the electron spin, including its generation, transport, port research in OSCs was given by Kazi and Sandipan.[12] and detection. The recent employment of spin freedom in ap- In 2006 and 2009, we made two efforts to summarize the plications enriches microelectronics and makes it possible to progress in organic spintronics at those dates, which appeared fabricate many novel devices. as chapters in two books, Progress in Ferromagnetism Re- The initial work on spintronics is to study the possibility search and Advances in Condensed Matter Physics.[13,14] of spin transport in nonferromagnetic materials. So far, based The present article is organized as follows. In Sections 2 on heterostructures or sandwich structures, spin injection and and 3, we review OSCs and spintronics, which are presented transport in superconductors, metals, and semiconductors have separately. In Section 4, the progress in organic spin injection been widely studied.[4–6] Most investigations have concen- and transport, and the developments in organic magnetic field trated on the current-induced spin polarization in semicon- effect (OMFE) are described. Finally, in Section 5, a summary ducting devices. Since organic functional materials have the is given. characteristics of semiconductors, it is natural to consider an alternative to normal semiconductors: the organic semicon- ductors. 2. Organic semiconductors Unlike the normal inorganic semiconductor materials, Organic spintronics include OSCs and spintronics. OSCs organic semiconductors (OSCs) are easily synthesized and contain small molecules as well as polymers. Small molecules ∗Project supported by the National Basic Research Program of China (Grant No. 2010CB923402), the National Natural Science Foundation of China (Grant Nos. 11174181 and 21161160445), and the 111 Project, China (Grant No. B13029). †Corresponding author. E-mail: [email protected] © 2014 Chinese Physical Society and IOP Publishing Ltd http://iopscience.iop.org/cpb http://cpb.iphy.ac.cn 058106-1 Chin. Phys. B Vol. 23, No. 5 (2014) 058106 such as tris(8-hydroxyquinolinato)aluminium (Alq3) and pen- chain bonding and the weak interchain interaction character- tacene are widely used to fabricate organic devices because istics, p electrons are delocalized, principally along the poly- these materials may have a high carrier mobility and have mer chain. A pristine polymer, such as polyacetylene, is a readily apparent functional properties. Variations in the sub- semiconductor or insulator depending upon the gap width be- stituents in the quinoline rings enrich the performance of these tween the highest occupied molecular orbital (HOMO) and devices. In 1976, Heeger et al. synthesized polyacetylene and the lowest unoccupied molecular orbital (LUMO). But when tuned its conductance by doping.[15] From then on, thousands it is doped or charge injected, the structure and the properties of organic conjugated polymers or organic materials, such as of a polymer may be changed dramatically. An extra elec- polythiophene (PT), polyparaphenylene (PPP), and polyacety- tron (or hole) will be trapped to form a charged soliton or lene (PA), have been synthesized. The conductance of these polaron. It is also discovered that two charged polarons can polymers covers the range from insulating, semiconducting, attract each other to form a bipolaron. All of these excita- to metallic. tions are localized in a spatial structure that is induced by the In 1987, Tang and Slyke were the first to demonstrate strong electron–lattice coupling in conjugated polymers. In a low-voltage and efficient thin-film LED and opened the 1979, Su, Schrieffer, and Heeger gave a simple tight-binding door to using organic small molecules for a new generation model to describe the ground state and the excitations in poly- of optoelectronic devices.[16] In 1990, Burroughes et al. ob- acetylene, which is well known as the SSH model.[28–30] They tained organic electroluminescent devices with common or- pointed out that solitons, polarons, or bipolarons in conducting ganic polymer poly phenylene vinylene (PPV).[17] From then conjugated polymers behave as quasi-particles with complete on, OLEDs and organic field-effect transistors (OFETs) were localization, stability, and integrity. In some small-molecule rapidly developed.[18–20] These devices are currently being in- crystals, it was also indicated that, due to the molecular fluctu- corporated into a variety of displays and are also potentially ation around the equilibrium position, an extra electron (hole) important for a wide range of other applications. Jiang et will form a self-trapped state, which is similar to a charged al. presented a theoretical design of poly(thienylene vinylene) excitation in a polymer.[31]