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شماره ركورد
24520
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شماره راهنما
PHY3 162
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نويسنده
البديري، رافد
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عنوان
وﻳﮋﮔﻲﻫﺎي اﻟﻜﺘﺮوﻧﻴﻜﻲ، ﻣﻐﻨﺎﻃﻴﺴﻲ و ﺗﻮﭘﻮﻟﻮژي ﻧﺎﻧﻮﺳﺎﺧﺘﺎرﻫﺎي ﮔﺮاﻓﻦ ﻣﺎﻧﻨﺪ
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مقطع تحصيلي
دكتري
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رشته تحصيلي
فيزيك - ماده چگال (پژوهش محور)
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دانشكده
فيزيك
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تاريخ دفاع
1404/01/27
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صفحه شمار
78 ص.
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استاد راهنما
ﻏﻼﻣﺮﺿﺎ راﺷﺪى
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استاد مشاور
ﻧﻔﻴﺴﻪ ﻧﻮرى
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كليدواژه فارسي
ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ , ﻣﻴﺪان ﻣﻐﻨﺎﻃﻴﺴﻲ ﻣﺘﻌﺎﻣﺪ , ﭘﻴﻮﻧﺪﻫﺎى آوﻳﺰان , ﻃﻴﻒ اﻧﺮژى , ﻋﺎﻳﻖ ﺗﻮﭘﻮﻟﻮژى
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چكيده فارسي
در اﻳﻦ ﭘﺎﻳﺎنﻧﺎﻣﻪ، وﻳﮋﮔﻲﻫﺎى ﻓﻴﺰﻳﻜﻲ ﻧﻘﻄﻪﻫﺎى ﻛﻮاﻧﺘﻮﻣﻲ ﺷﺶﮔﻮﺷﻲ و ﻣﺜﻠﺜﻲ ﺑﻴﺴﻤﻮت ﺑﺎ اﺗﻢﻫﺎى ﻟﺒﻪاى زﻳﮕﺰاگ و آرﻣﭽﻴﺮ ﻣﺘﺼﻞ ﺑﻪ اﺗﻢﻫﺎى ﻫﻴﺪروژن را ﺑﺮرﺳﻲ ﻛﺮده و ﻧﺘﺎﻳﺞ آن را ﺑﺎ ﻧﺘﺎﻳﺞ ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺑﻴﺴﻤﻮت ﺑﺪون اﺗﺼﺎل ﺑﻪ اﺗﻢﻫﺎى ﻫﻴﺪروژن ﻣﻘﺎﻳﺴﻪ ﻣﻲﻛﻨﻴﻢ. اﺑﺘﺪا ﺑﺎ اﺳﺘﻔﺎده از ﻣﺪل ﺑﺴﺘﮕﻲ ﻗﻮى ﭼﻨﺪ اورﺑﻴﺘﺎﻟﻲ، ﻃﻴﻒ اﻧﺮژى ﻧﻘﻄﻪﻫﺎى ﻛﻮاﻧﺘﻮﻣﻲ اﺷﺎره ﺷﺪه در ﺑﺎﻻ ﺑﺮرﺳﻲ ﻣﻲﺷﻮد. ﻧﺘﺎﻳﺞ ﻧﺸﺎن ﻣﻲ دﻫﺪ ﻛﻪ ﺷﺮاﻳﻂ ﻣﺮزى ﺑﺴﺘﻪ ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺑﻴﺴﻤﻮت ﻣﺘﺼﻞ ﺑﻪ اﺗﻢ ﻫﻴﺪروژن، ﺑﺎﻋﺚ ﭘﺪﻳﺪار ﺷﺪن ﺗﻌﺪادى ﻧﻮار اﻧﺮژى در ﻣﺤﺪوده ﮔﺎف اﻧﺮژى ﻧﺎﻧﻮﻻﻳﻪﻫﺎى ﺑﻴﺴﻤﻮت )ﻣﻮﺳﻮم ﺑﻪ ﺣﺎﻟﺖﻫﺎى ﻟﺒﻪاى( ﺷﺪه اﺳﺖ. ﺗﻌﺪاد ﺣﺎﻟﺖﻫﺎى ﻟﺒﻪاى ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺑﻴﺴﻤﻮت ﻣﺘﺼﻞ ﺑﻪ اﺗﻢ ﻫﻴﺪروژن در ﻣﻘﺎﻳﺴﻪ ﺑﺎ ﺗﻌﺪاد ﺣﺎﻟﺖﻫﺎى ﻟﺒﻪاى ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺑﻴﺴﻤﻮت ﺑﺪون اﺗﺼﺎل ﺑﻪ اﺗﻢ ﻫﻴﺪروژن، ﺑﺴﻴﺎر ﻛﻤﺘﺮ اﺳﺖ. دﻟﻴﻞ اﻳﻦ اﻣﺮ اﻳﻦ اﺳﺖ ﻛﻪ ﺗﻌﺪادى ﭘﻴﻮﻧﺪﻫﺎى ﻣﻌﻠﻖ در ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺑﻴﺴﻤﻮت ﺑﺪون اﺗﺼﺎل ﺑﻪ ﻫﻴﺪروژن، وارد ﭘﻴﻮﻧﺪ ﺑﺎ اﺗﻢﻫﺎى ﻫﻴﺪروژن ﺷﺪه و ﺑﺎﻋﺚ اﺷﺒﺎع و ﺧﺮوج آنﻫﺎ از ﻣﺤﺪوده ﮔﺎف اﻧﺮژى ﻧﺎﻧﻮﺻﻔﺤﺎت ﺑﻴﺴﻤﻮت ﻣﻲﺷﻮد. ﻫﻤﭽﻨﻴﻦ ﻣﺸﺎﻫﺪه ﻛﺮدﻳﻢ ﻛﻪ ﺗﻌﺪاد ﺣﺎﻟﺖﻫﺎى ﻟﺒﻪاى ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﻣﺜﻠﺜﻲ ﺑﺎ ﻟﺒﻪى آرﻣﭽﻴﺮ، ﺑﻴﺸﺘﺮ از ﺗﻌﺪاد ﺣﺎﻟﺖﻫﺎى ﻟﺒﻪاى ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﻣﺜﻠﺜﻲ ﺑﺎ ﻟﺒﻪى زﻳﮕﺰاگ و ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺷﺶﮔﻮﺷﻲ ﺑﺎ ﻟﺒﻪﻫﺎى زﻳﮕﺰاگ و آرﻣﭽﻴﺮ ﻫﺴﺘﻨﺪ. در اداﻣﻪ ﺑﺎ ﻣﺤﺎﺳﺒﻪ ﭼﮕﺎﻟﻲ اﻟﻜﺘﺮوﻧﻲ ﺣﺎﻟﺖﻫﺎ، ﻣﺸﺎﻫﺪه ﻛﺮدﻳﻢ ﻛﻪ اﺗﻢﻫﺎى Bi ﻟﺒﻪاى ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ، ﻧﻘﺶ ﺑﺴﻴﺎر ﻣﻬﻤﺘﺮى ﻧﺴﺒﺖ ﺑﻪ اﺗﻢﻫﺎى ﺣﺠﻤﻲ در ﺳﺎﺧﺖ اﻳﻦ ﺣﺎﻟﺖﻫﺎى ﻟﺒﻪاى دارﻧﺪ. ﺳﭙﺲ ﺗﻤﺎم ﻣﺤﺎﺳﺒﺎت ﺑﺎﻻ را ﺑﺎ اﻋﻤﺎل ﻣﻴﺪان ﻣﻐﻨﺎﻃﻴﺴﻲ ﻣﺘﻌﺎﻣﺪ ﺑﺮ ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺑﻴﺴﻤﻮت اﻧﺠﺎم ﻣﻲدﻫﻴﻢ. ﺑﺎ اﻋﻤﺎل ﻣﻴﺪان ﻣﻐﻨﺎﻃﻴﺴﻲ ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺑﻴﺴﻤﻮت ﻣﺘﺼﻞ ﺑﻪ اﺗﻢ ﻫﻴﺪروژن، ﻣﺸﺎﻫﺪه ﻛﺮدهاﻳﻢ ﻛﻪ ﺗﻌﺪاد ﺳﻄﻮح اﻧﺮژى در ﻣﺤﺪوده ﮔﺎف اﻧﺮژى در ﻣﻘﺎﻳﺴﻪ ﺑﺎ ﺗﻌﺪاد ﺳﻄﻮح اﻧﺮژى ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺑﺪون اﺗﺼﺎل ﺑﻪ اﺗﻢ ﻫﻴﺪروژن در ﻣﺤﺪوده ﮔﺎف اﻧﺮژى ﻛﺎﻫﺶ ﻣﻲﻳﺎﺑﺪ ﻛﻪ دﻟﻴﻞ اﻳﻦ اﻣﺮ ﻫﻤﺎن اﺷﺒﺎع اﺗﻢﻫﺎى آوﻳﺰان ﺑﺎ اﺗﻢﻫﺎى ﻫﻴﺪروژن اﺳﺖ. ﺑﻨﺎﺑﺮاﻳﻦ ﺗﻌﺪادى ﺣﺎﻟﺖﻫﺎ در ﻣﺤﺪوده ﮔﺎف اﻧﺮژى ﺣﺬف ﺷﺪه و ﺗﻌﺪادى ﻫﻢ در ﻫﻤﺎن ﻣﺤﺪوده ﺑﺎﻗﻲ ﻣﻲﻣﺎﻧﻨﺪ. ﺑﺎ ﭼﺸﻤﭙﻮﺷﻲ از ﺑﺮﻫﻤﻜﻨﺶ اﺳﭙﻴﻦ ﻣﺪار ﻣﺸﺎﻫﺪه ﻛﺮدهاﻳﻢ ﻛﻪ ﺣﺎﻟﺖﻫﺎى ﺑﺎﻗﻲ ﻣﺎﻧﺪه در ﻣﺤﺪوده ﮔﺎف اﻧﺮژى ﻧﻴﺰ ازﺑﻴﻦ ﻣﻲروﻧﺪ ﻛﻪ اﻳﻦ اﻣﺮ ﻧﺸﺎندﻫﻨﺪه ﺗﻮﭘﻮﻟﻮژى ﺑﻮدن ﻧﻘﺎط ﻛﻮاﻧﺘﻮﻣﻲ ﺑﻴﺴﻤﻮت ﻣﺘﺼﻞ ﺑﻪ اﺗﻢ ﻫﻴﺪروژن اﺳﺖ. ﻫﻤﭽﻨﻴﻦ ﻣﺸﺎﻫﺪه ﻛﺮدهاﻳﻢ ﻛﻪ در ﻣﻴﺪانﻫﺎى ﻣﻐﻨﺎﻃﻴﺴﻲ ﺿﻌﻴﻒ، ﺗﻌﺪاد ﺑﺴﻴﺎر زﻳﺎدى از ﺣﺎﻟﺖﻫﺎى اﻧﺮژى ﻛﻪ ﻣﻌﺮوف ﺑﻪ ﺳﻄﻮح ﻻﻧﺪاﺋﻮ ﻫﺴﺘﻨﺪ، اﻳﺠﺎد ﻣﻲﺷﻮﻧﺪ ﻛﻪ ﺑﺎ ﻣﺤﺎﺳﺒﻪ ﭼﮕﺎﻟﻲ اﻟﻜﺘﺮوﻧﻲ ﺣﺎﻟﺖﻫﺎ، ﻣﺘﻮﺟﻪ ﺷﺪﻳﻢ ﻛﻪ اﺗﻢﻫﺎى ﻟﺒﻪاى Bi ﻧﻘﺶ ﻣﻬﻤﻲ در ﺗﺸﻜﻴﻞ اﻳﻦ ﺳﻄﻮح ﻻﻧﺪاﺋﻮ دارﻧﺪ. ﺑﺎ اﻓﺰاﻳﺶ ﻣﻴﺪان ﻣﻐﻨﺎﻃﻴﺴﻲ ﺗﻌﺪاد زﻳﺎدى ازﺣﺎﻟﺖﻫﺎى اﻧﺮژى ﺑﺮ روى ﺳﻄﻮح ﻻﻧﺪاﺋﻮ ﻗﺮار ﻣﻲﮔﻴﺮﻧﺪ و ﺳﻄﻮح ﻻﻧﺪاﺋﻮ i ام را ﺑﻪ ﺳﻄﻮح ﻻﻧﺪاﺋﻮi+1 ام ﻣﺘﺼﻞ ﻣﻲﻛﻨﻨﺪ ﻛﻪ ﺑﺎ ﻣﺤﺎﺳﺒﻪ ﭼﮕﺎﻟﻲ اﻟﻜﺘﺮوﻧﻲ ﺣﺎﻟﺖﻫﺎ ﺑﻪ اﻳﻦ ﻧﺘﻴﺠﻪ رﺳﻴﺪهاﻳﻢ ﻛﻪ اﺗﻢﻫﺎى ﺣﺠﻤﻲ ﺳﺎﺧﺘﺎر در ﺗﺸﻜﻴﻞ اﻳﻦ اﺗﺼﺎلدﻫﻨﺪهﻫﺎ ﻧﻘﺶ دارﻧﺪ.
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كليدواژه لاتين
Quantum Dots , perpendicular Magnetic Field , Dangling Bonds , Energy Spectrum , Topological Insulators
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عنوان لاتين
Electronic, magnetic and topological properties of graphene-like materials
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گروه آموزشي
فيزيك ماده چگال
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چكيده لاتين
We investigate the physical properties of triangular and hexagonal Buckled-Bismuth quantum dots with zigzag and armchair boundary atoms passivated by hydrogen atoms. Also using the multi-orbital tight-binding model, the energy spectra of the aforementioned structures are studied. We obtained that, the H-passivation on the boundary atoms of considered quantum dots decreases the number of states within the energy gap value (edge states) compared to the number of edge modes of these structures without H-passivation. So, some states are saturated by H atoms and removed from the energy gap interval in the H-passivation quantum dots. These removed states are known as dangling bonds. We also obtained that the number of edge states in armchair triangular Bismuth quantum dot is more than other ones. By computing the probability density of states, we understand that edge atoms form the mentioned edge states. Also, we study the energy spectra of the above H-passivated quantum dots under the perpendicular magnetic fields. We obtained that, by turning on and off the spin–orbit-coupling interaction, the removed edge states (saturated by H atoms) are trivial modes and remained edge states are non-trivial ones (protected symmetry). Therefore, H-passivated quantum dots can be applied to measure the fluctuation in the conductance of their edge states. Also in the presence of magnetic field, we see Landau levels. Finally we find that, for forming these Landau levels, the edge atoms are more important than bulk atoms.
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تعداد فصل ها
3
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لينک به اين مدرک :
