Study of spin transport in polyfluorene films
Study of spin transport in polyfluorene films
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DOI：
10.1117/1.jpe.8.032212
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发表时间：
2018-05
影响因子：
1.7
通讯作者：
Haoliang Liu;M. Groesbeck;E. Lafalce;Xiaojie Liu;Z. Vardeny
中科院分区：
文献类型：
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作者：
Haoliang Liu;M. Groesbeck;E. Lafalce;Xiaojie Liu;Z. Vardeny
抽象的。在室温下，我们在NiFe/polyfluorene/Pt三层器件中，用自旋泵技术研究了聚芴（一种π共轭聚合物）薄膜中的自旋输运.在铁磁共振条件下，通过微波激发NiFe磁矩，在聚合物薄膜中产生纯自旋电流（无载流子注入）。通过铁磁体/聚合物界面的感应自旋电流穿过聚合物层，并由器件中的Pt覆盖层检测，在该器件中，它通过逆自旋霍尔效应转换为电流。通过改变三层结构中聚合物的厚度，我们成功地测定了聚芴薄膜中的自旋扩散长度λS，得到λS = 118 ± 9 nm。我们还使用飞行时间技术测量了聚芴膜中的电荷载流子迁移率μ，发现它受到色散输运的影响。根据所得到的λS和μ值，我们估算了聚芴在室温下的自旋弛豫时间为1.5 μs。
Abstract. We have investigated spin transport in films of polyfluorene, a π-conjugated polymer, using the technique of “spin pumping” from a ferromagnet substrate, namely Ni80Fe20 in a NiFe/polyfluorene/Pt trilayer device at room temperature. Pure spin current (without carrier injection) is generated in the polymer film by microwave excitation of the NiFe magnetic moment at ferromagnetic resonance conditions. The induced spin current through the ferromagnet/polymer interface crosses the polymer layer and is detected by a Pt overlayer in the device, where it is converted into electric current via the inverse spin Hall effect. We have successfully determined the spin diffusion length, λS, in the polyfluorene film by varying the polymer thickness in the trilayer structure, and found λS = 118 ± 9 nm. We also measured the charge-carrier mobility, μ in polyfluorene film using the time-of-flight technique and found it to be affected by dispersive transport. From the obtained λS and μ values, we estimated the spin relaxation time in polyfluorene to be ∼5 μs at room temperature.