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Electron transport in GaAs heterostr...

Harvard University.

Electron transport in GaAs heterostructures at various magnetic field strengths.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Electron transport in GaAs heterostructures at various magnetic field strengths.
Author:	Miller, Jeffrey Burnham.
Description:	128 p.
Notes:	Adviser: Charles M. Marcus.
Notes:	Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1033.
Contained By:	Dissertation Abstracts International68-02B.
Subject:	Physics, Condensed Matter.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3251298

Electron transport in GaAs heterostructures at various magnetic field strengths.
Miller, Jeffrey Burnham.

Electron transport in GaAs heterostructures at various magnetic field strengths. - 128 p.

Adviser: Charles M. Marcus.

Thesis (Ph.D.)--Harvard University, 2007.

In the first set of experiments---the low-field experiments---we studied the effect of spin-orbit coupling. We tuned the strength of spin-orbit coupling from the weak localization regime to the antilocalization regime using in situ gate control. Using a new theory, we separately extracted the values for the three material-dependent spin-orbit constants. We also measured the average and variance of conductance in assorted quantum dots, with and without strong spin-orbit coupling, and found quantitative agreement with recent random matrix theory predictions, as long as we also properly included the effects of parallel magnetic field.Subjects--Topical Terms:

226939
Physics, Condensed Matter.

Electron transport in GaAs heterostructures at various magnetic field strengths.
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040 $a UMI $c UMI
100 0 $a Miller, Jeffrey Burnham. $3 264335
245 1 0 $a Electron transport in GaAs heterostructures at various magnetic field strengths.
300 $a 128 p.
500 $a Adviser: Charles M. Marcus.
500 $a Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1033.
502 $a Thesis (Ph.D.)--Harvard University, 2007.
520 # $a In the first set of experiments---the low-field experiments---we studied the effect of spin-orbit coupling. We tuned the strength of spin-orbit coupling from the weak localization regime to the antilocalization regime using in situ gate control. Using a new theory, we separately extracted the values for the three material-dependent spin-orbit constants. We also measured the average and variance of conductance in assorted quantum dots, with and without strong spin-orbit coupling, and found quantitative agreement with recent random matrix theory predictions, as long as we also properly included the effects of parallel magnetic field.
520 # $a In the second set of experiments---the high-field experiments---we studied the transport properties of quantum point contacts (QPC) fabricated on a GaAs/AlGaAs two dimensional electron gas that exhibits excellent bulk fractional quantum Hall effect, including a strong plateau in the Hall resistance at Landau level filling fraction v = 5/2. We demonstrate that the v = 5/2 state can survive in QPCs with 1.2 mum and 0.8 mum spacings between the gates. However, in our sample, all signatures of the 5/2 state are completely gone in a 0.5 mum QPC. We study the temperature dependence at v = 5/2 in the QPC and find two distinct regimes: at temperatures below 19 mK a we find a plateau-like feature with resistance near (but above) the bulk quantized value of 0.4 h/e2, while at higher temperatures this plateau does not form. We study the dc-current-bias (Idc) dependence of the plateau-like feature, and find a peak in the differential resistance at I dc = 0 and a dip around Idc &sim; 1.2nA, consistent with quasiparticle tunneling between fractional edge states. In a QPC with 0.5 mum spacing between the gates, we do not observe a plateau-like feature at any temperature, and the I dc characteristic is flat for the entire range between v = 3 and v = 2.
520 # $a This thesis describes two sets of experiments which explore transport in a two-dimensional electron gas in the presence of a magnetic field. We used nanofabrication techniques to make samples on GaAs/AlGaAs heterostructures, and measured the samples at cryogenic temperatures using ac-lock-in techniques.
590 $a School code: 0084.
650 # 0 $a Physics, Condensed Matter. $3 226939
690 $a 0611
710 0 # $a Harvard University. $3 212445
773 0 # $g 68-02B. $t Dissertation Abstracts International
790 $a 0084
790 1 0 $a Marcus, Charles M., $e advisor
791 $a Ph.D.
792 $a 2007
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