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Heidi Potts Position:    PostDoc E-mail:    heidi.potts@ftf.lth.se Phone:    +46 (0)46-2224369 Cell phone:    Room:    B107 Address:    Professorsgatan 1 22363 Lund       Sweden University:    Lund University Division:    Solid State Physics Research Area(s):    Materials Science Quantum Physics Nanoelectronics- & photonics Interests:    Crystal phase QDs

Research:

I am currently investigating the interaction of spins and electrons in parallel-couple quantum dots (QDs). Recent advances in crystal phase engineering allow to create a QD consisting of a thin zinc-blende section between two wurtzite tunnel barriers in InAs nanowires [1]. Such a QD can be split into two parallel coupled QDs using two local sidegates and a global backgate. This system can be considered an artificial molecule, for which the electron population on the two dots can be changed separately, and the tunnel coupling between the two dots can be tuned [2,3,4].


a) Device schematic of a parallel-coupled crystal phase QD in an InAs nanowire. b) Honeycomb stability diagram schematic.

At the moment our focus lies on QDs with transparent tunnel barriers. This allows us to study both the well-known spin-1/2 Kondo effect, as well as the orbital Kondo effect which is unique in parallel-coupled QDs. We further investigate co-tunneling transport to study the effective g-factor. In certain conditions we find a huge orbital contribution to the g-factor, resulting in values above 40. Finally we also study the formation of singlet and triplet states when two electrons are present in the QDs.

a) Schematic of different transport mechanisms. b) Honeycomb stability diagram. c)-d) Stability diagram recorded along the green vector at B=0T and B=1T. The spin and orbital Kondo effect can be observed.


a) Honeycomb stability diagram. b) Stability diagram along the green vector at B=300mT aligned with the nanowire. c) B-field rotation in the plane of the nanowire, showing a huge g-factor anisotropy.

[1] M. Nilsson et al. PRB 93, 195423 (2016)
[2] M. Nilsson et al. Nano Letters 17, 7847 (2017)
[3] M. Nilsson et al. PRL (accepted 27 July 2018)
[4] C. Thelander et al arXiv:1808.06431

Recent publications:

Tilting catalyst-free InAs nanowires by 3D- twinning and unusual growth directions. Crystal Growth & Design 17, 3596 (2017)

Tuning growth direction of catalyst-free InAs(Sb) nanowires with indiumdroplets. Nanotechnology 28, 054001 (2017)

FromTwinning to Pure Zincblende Catalyst-Free InAs(Sb) Nanowires. Nano Letters 16, 637 (2016)

A complete list of publications can be found on ResearchGate.