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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, quantum rings, Kondo transport, g-factor manipulation

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 thin quantum well consisting of a thin zinc-blende section between two wurtzite tunnel barriers in InAs nanowires [1]. Such a quantum well 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 the investigation of quantum rings, which can be formed by coupling two QDs in two two points. These quantum rings exhibit anisotropic g-factors of up to 80, due to a large orbital contribution. The device architecture furthermore allows to electrostatically tune the g-factors by modification of the ring quality [5]. We also investigate the Kondo effect in parallel-coupled QDs and quantum rings, and show selective tuning of the spin and orbital contributions to the Kondo resonance [6]. Finally, we also study the formation of singlet and triplet states in quantum rings, and show that the ground state of the system depends on the quality of the quantum ring.

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.

[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 121, 156802 (2018)
[4] C. Thelander et al. PRB 98, 245305 (2018)
[5] H. Potts et al. Nature Communications 10, 5740 (2019)
[6] H. Potts et al. arxiv:1912.05181

Recent publications:

Selective tuning of spin-orbital Kondo contributions in parallel-coupled quantum dots. arxiv:1912.05181

Electrical control of spins and giant g-factors in ring-like coupled quantum dots. Nature Communcations 10, 5740 (2019) arxiv:1905.06616

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.