Bistability in the Tunnelling Current through a Ring of N Coupled Quantum Dots

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Title:	Bistability in the Tunnelling Current through a Ring of N Coupled Quantum Dots
Authors:	Shiau,SY;Chang,YC;Kuo,DMT
Contributors:	電機工程學系
Keywords:	LOCALIZED MAGNETIC STATES;INTRINSIC BISTABILITY;COULOMB INTERACTION;NONVOLATILE MEMORY;PHASE LAPSES;THIN-FILM;MODEL;HYSTERESIS;TRANSMISSION;CONDUCTANCE
Date:	2011
Issue Date:	2012-03-28 10:13:55 (UTC+8)
Publisher:	國立中央大學
Abstract:	We study bistability in the electron transport through a ring of N coupled quantum dots with two orbitals in each dot. One orbital is localized (called b orbital) and coupling of the b orbitals in any two dots is negligible; the other is delocalized in the plane of the ring (called d orbital), due to coupling of the d orbitals in the neighboring dots, as described by a tight-binding model. The d orbitals thereby form a band with finite width. The b and d orbitals are connected to the source and drain electrodes with a voltage bias V, allowing the electron tunnelling. Tunnelling current is calculated by using a nonequilibrium Green function method recently developed to treat nanostructures with multiple energy levels. We find a bistable effect in the tunnelling current as a function of bias V, when the size N greater than or similar to 50; this effect scales with the size N and becomes sizable at N similar to 100. The temperature effect on bistability is also discussed. In comparison, mean-field treatment tends to overestimate the bistable effect.
Relation:	JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
Appears in Collections:	[Department of Electrical Engineering] journal & Dissertation

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