جریانهای خالص اسپینی و قطبیده اسپینی در مولکول بنزن متصل شده به سه رابط گرافینی

نویسندگان

1 گروه فیزیک، دانشگاه آزاد اسالمی، واحد علوم و تحقیقات، تهران، ایران.

2 گروه فیزیک، دانشکده فیزیک، دانشگاه علم و صنعت ایران، تهران

چکیده

در این پژوهش با استفاده از روش نظری تابع گرین جریان های وابسته به اسپین در پیوندگاه بنزنی مورد مطالعه قرار گرفته است. پیوندگاه مولکولی، به سه نانو نوار گرافینی نیمه نامتناهی، تحت عنوان رابط های خروجی متصل شده است. به منظور شکستن تبهگنی الکترون ها با حالت های اسپینی متفاوت، میدان مغناطیسی تبادلی بر پیوندگاه مولکولی اعمال می شود. نتایج نشان می دهند که با انتخاب مناسب هندسه ی ساختار و همچنین با تنظیم پتانسیل های شیمیایی، جریان اسپینی خالص و همچنین جریان اسپینی کاملاً قطبیده، در یکی از رابط های خروجی ایجاد می شوند. مزیت بکارگیری مولکول بنزن در مرکز پیوندگاه پیدایش جریان خالص اسپینی در ولتاژهای متعدد است. در ادامه، جداسازی فضایی جریان های قطبیده اسپینی در پیوندگاه بنزنی بررسی شده است. نتایج نشان می دهند با در نظر گرفتن ساختار دیگری از پیوندگاه بنزنی و تنظیم مجدد پتانسیل های شیمیایی و همچنین شدت و موقعیت میدان مغناطیسی تبادلی، جریان غیرقطبیده ورودی به جریان های خروجی کاملاً قطبیده ی اسپینی تبدیل می شود، به طوریکه جریان های قطبیده ی عبوری از دو رابط خروجی دارای اسپین های متضاد هستند.

کلیدواژه‌ها


عنوان مقاله [English]

Pure spin and spin polarized currents in the benzene molecule connected to three graphene leads

نویسندگان [English]

  • N. Farshchi 1
  • M. Esmaeilzadeh 2
  • L. Eslami 1
  • S. M . Elahi 1
  • E. Darabi 1
1 Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran.
2 Department of Physics, Iran University of Science and Technology, Tehran.
چکیده [English]

In this work, we present a theoretical study of a molecular junction based on benzene molecule at the center of the junction with three semi infinite graphene nanoribbons as external terminals to explore spin dependent current properties by using Green´s function method. The exchange magnetic field is exerted on the molecular junction in order to break the degeneracy of electrons with spin up and spin down states. It is shown that by changing chemical potential and choosing a proper geometry of the structure we can control the direction of spin dependent electron current such that in one of the external terminals electrons with different spin states flow in opposite directions; therefore, in that terminal the pure spin current can be attainable. In addition, we show that by considering another form of benzene Y-shape junction and by readjusting chemical potentials of the external terminals, we can set the system in a way that a totally unpolarized incoming spin current split into spin up and spin down currents which transmit through different output terminals. In this case, the proposed system can be considered as a Stern-Gerlach device.
 

کلیدواژه‌ها [English]

  • Molecular junction
  • Benzene molecule
  • Pure spin current
  • Spin polarized current
  • Graphene nanoribbon
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