中文
Published date:2015-01-14    Provided by:School of Science
Title: Impurity-band transport in organic spin valves

Guest Speaker: Zhi-Gang Yu

Time: 2015-1-19 (Monday), 15:00-16:30

Location: Conference Room (7205), School of Science

 

Abstract

The central phenomenon in the field of organic spintronics is the large magnetoresistance in thick organic spin valves. A prerequisite for understanding the magnetoresistance is a reliable description of the device resistance, or the I-V characteristics. In this talk I show that the observed I-V characteristics in the organic spin valves is incompatible with charge injection into the organic’s lowest unoccupied molecular orbital or highest occupied molecular orbital but can be explained by electrons tunnelling into a broad impurity band located in the gap between these molecular orbitals. Voltage drop takes place mainly across depletion layers at the two electrode/organic interfaces, giving rise to electrode-limited charge transport. Spin-dependent electron tunnelling into the impurity band from the ferromagnetic electrodes results in spin accumulations inside the organic, which rapidly diffuses through the organic primarily via the exchange between impurity-band electrons. This picture explains the major magnetoresistance features and predicts enhanced capacitance in these devices.

 

Biography

Zhi-Gang YuSenior Research ScientistSRI International(斯坦福国际研究院), USA

 

EDUCATION
1991-1996 Fudan University, China, PhD in Theoretical Condensed Matter Physics
1986-1991 University of Science and Technology of China (USTC), BS in Theoretical Physics

 

QUALIFICATION HIGHLIGHTS
Deep understanding of and broad experience in condensed matter physics, quantum statistical physics,and materials physics
Effective in establishing research directions, winning government funding, and leading multiple projects.
Experienced in modeling of a variety of complex materials, including semiconductors, conducting polymers,transition-metal oxides, and biological systems for understanding and predicting their unusual electronic,optical, and transport properties, as well as novel electronic, spintronic, and optoelectronic device structures based on them
Self-motivated team player; skilled in communicating with scientists with di erent expertise
Able to formulate innovative solutions to challenges in complex systems; strong capabilities in analytical methods, algorithm development, and programming  
Excellent written and verbal communication skills

 

REFERENCES

[1] Z. G. Yu, Impurity-band transport in organic spin valves, Nature Comm. 5, 4842 (2014).

[2] Z. G. Yu, Suppression of the Hanle effect in organic spintronic devices, Phys. Rev. Lett. 111, 016601 (2013).


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