Determination of spin injection and transport in a ferromagnet/organic semiconductor heterojunction by two-photon photoemission

被引:86
作者
Cinchetti, Mirko [1 ,2 ]
Heimer, Kathrin [1 ,2 ]
Wuestenberg, Jan-Peter [1 ,2 ]
Andreyev, Oleksiy [3 ]
Bauer, Michael [3 ]
Lach, Stefan [1 ,2 ]
Ziegler, Christiane [1 ,2 ]
Gao, Yongli [4 ,5 ]
Aeschlimann, Martin [1 ,2 ]
机构
[1] Univ Kaiserslautern, Dept Phys, D-67663 Kaiserslautern, Germany
[2] Univ Kaiserslautern, Res Ctr OPTIMAS, D-67663 Kaiserslautern, Germany
[3] Univ Kiel, Inst Expt & Angew Phys, D-24118 Kiel, Germany
[4] Cent S Univ, Dept Phys, Changsha 410083, Peoples R China
[5] Univ Rochester, Dept Phys & Astron, Rochester, NY 14627 USA
关键词
ORGANIC SEMICONDUCTOR; COPPER PHTHALOCYANINE; SPINTRONICS; TEMPERATURE;
D O I
10.1038/NMAT2334
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
A fundamental prerequisite for the implementation of organic semiconductors (OSCs) in spintronics devices is the still missing basic knowledge about spin injection and transport in OSCs. Here, we consider a model system consisting of a high-quality interface between the ferromagnet cobalt and the OSC copper phthalocyanine (CuPc). We focus on interfacial effects on spin injection and on the spin transport properties of CuPc. Using spin-resolved two-photon photoemission, we have measured directly and in situ the efficiency of spin injection at the cobalt-CuPc interface. We report a spin injection efficiency of 85-90% for injection into unoccupied molecular orbitals of CuPc. Moreover, we estimate an electron inelastic mean free path in CuPc in the range of 1nm and a 10-30 times higher quasi-elastic spin-flip length. We demonstrate that quasi-elastic spin-flip processes with energy loss <= 200 meV are the dominant microscopic mechanism limiting the spin diffusion length in CuPc.
引用
收藏
页码:115 / 119
页数:5
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