ELECTRON TEMPERATURE OF BALLISTIC CURRENT IN QUANTUM POINT CONTACT

• Main Authors: Chun-ChihCheng, 鄭鈞之
• Other Authors: Tse-Ming Chen
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/02108063583800565818

碩士 === 國立成功大學 === 物理學系碩博士班 === 100 === Quantum point contacts (QPC), i.e., quasi one-dimensional (1D) conductors, have recently been suggested to form the basis of a fully electrical method for the creation and manipulation of spin polarization as well as spin-polarized current [1,2,3]. It has been shown that the all-electric spin injection can be achieved when the momentum degeneracy is lifted either by spin-orbit interaction or a large source-drain dc bias. However, there has been little understanding of other physical properties about the QPC, which remains of significant importance before its application in future spintronics and quantum information processing can be achieved. I will demonstrate the temperature measurement of the electron transport through a QPC using the intrinsic property of quantum dot (QD). Moreover, I will show the temperature properties of QPC in the non-Ohmic regime wherein a dc source-drain bias was applied. The idea is the following: a device is constituted of a QPC, serving as a charge/spin injector, and a QD, which acts as a detector in this work. The electrons will be injected through the QPC from a source, and tunnel into the QD due to an applied magnetic field causing it to rotate, Coulomb blockade oscillations were then observed and the resonance peaks were used as a thermometer to measure the temperature dependence of the electrons of current in the QPC. The result shows that the temperature will not change during the transportation, which implies that it may be a ballistic transport for electron through a QPC which shows that the spin relaxation would be little affected by source-drain bias, which is important for spintronics and quantum information processing.