Peter Märki

Last Name

Märki

First Name

Peter

ORCID

0000-0002-0596-076X

Organisational unit

03439 - Ensslin, Klaus / Ensslin, Klaus

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Publications 1 - 8 of 8

Electronic g factor and magnetotransport in InSb quantum wells
Lei, Zijin; Lehner, Christian A.; Rubi, Km; et al. (2020)
Physical Review Research
High mobility InSb quantum wells with tunable carrier densities are investigated by transport experiments in magnetic fields tilted with respect to the sample normal. We employ the coincidence method and the temperature dependence of the Shubnikov–de Haas oscillations and find a value for the effective g factor of |g^∗| = 35±4 and a value for the effective mass of m^∗ ≈ 0.017 m_e, where m_e is the free electron mass. Our measurements are performed in a magnetic field and a density range where the enhancement mechanism of the effective g factor can be neglected. Accordingly, the obtained effective g factor and the effective mass can be explained in a single-particle picture. Additionally, we explore the magnetotransport up to magnetic fields of 35 T and do not find features related to the fractional quantum Hall effect.
Observation of quantum Hall interferometer phase jumps due to a change in the number of bulk quasiparticles
Röösli, Marc P.; Brem, Lars; Kratochwil, Benedikt; et al. (2020)
Physical Review B
Spectroscopy of equilibrium and nonequilibrium charge transfer in semiconductor quantum structures
Rössler, Clemens; Burkhard, S.; Krähenmann, Tobias; et al. (2014)
Physical Review B
We investigate equilibrium and nonequilibrium charge-transfer processes by performing high-resolution transport spectroscopy. Using electrostatically defined quantum dots for energy-selective emission and detection, we achieved very high spectral resolution and a high degree of tunability of relevant experimental parameters. Most importantly, we observe that the spectral width of elastically transferred electrons can be substantially smaller than the linewidth of a thermally broadened Coulomb peak. This finding indicates that the charge-transfer process is fast compared to the electron-phonon interaction time. By drawing an analogy to double quantum dots, we argue that the spectral width of the elastic resonance is determined by the lifetime broadening hΓ of the emitter and detector states. Good agreement with the model is found also in an experiment in which the charge transfer is in the regime hΓkBT. By performing spectroscopy below the Fermi energy, we furthermore observe elastic and inelastic transfer of holes. © 2014 American Physical Society.
Fractional Coulomb blockade for quasi-particle tunneling between edge channels
Röösli, Marc P.; Hug, Michael; Nicoli, Giorgio; et al. (2021)
Science Advances
In the fractional quantum Hall effect, the elementary excitations are quasi-particles with fractional charges as predicted by theory and demonstrated by noise and interference experiments. We observe Coulomb blockade of fractional charges in the measured magneto-conductance of a 1.4-micron-wide quantum dot. Interaction-driven edge reconstruction separates the dot into concentric compressible regions with fractionally charged excitations and incompressible regions acting as tunnel barriers for quasi-particles. Our data show the formation of incompressible regions of filling factors 2/3 and 1/3. Comparing data at fractional filling factors to filling factor 2, we extract the fractional quasi-particle charge e*/e = 0.32 ± 0.03 and 0.35 ± 0.05. Our investigations extend and complement quantum Hall Fabry-Pérot interference experiments investigating the nature of anyonic fractional quasi-particles.
Spin-Selective Equilibration among Integer Quantum Hall Edge Channels
Nicoli, Giorgio; Adam, Christoph; Röösli, Marc P.; et al. (2022)
Physical Review Letters
The equilibration between quantum Hall edge modes is known to depend on the disorder potential and the steepness of the edge. Modern samples with higher mobilities and setups with lower electron temperatures call for a further exploration of the topic. We develop a framework to systematically measure and analyze the equilibration of many (up to 8) integer edge modes. Our results show that spin-selective coupling dominates even for non-neighboring channels with parallel spin. Changes in magnetic field and bulk density let us control the equilibration until it is almost completely suppressed and dominated only by individual microscopic scatterers. This method could serve as a guideline to investigate and design improved devices, and to study fractional and other exotic states.
Quantum dot thermometry at ultra-low temperature in a dilution refrigerator with a 4He immersion cell
Nicoli, G.; Märki, Peter; Bräm, Beat A.; et al. (2019)
Review of Scientific Instruments
Gate-defined two-dimensional hole and electron systems in an undoped InSb quantum well
Lei, Zijin; Cheah, Erik; Krizek, Filip; et al. (2023)
Physical Review Research
Quantum transport measurements are performed in gate-defined, high-quality, two-dimensional hole and electron systems in an undoped InSb quantum well. For both polarities, the carrier systems show tunable spin-orbit interaction as extracted from weak antilocalization measurements. The effective mass of InSb holes strongly increases with carrier density as determined from the temperature dependence of Shubnikov–de Haas oscillations. Coincidence measurements in a tilted magnetic field are performed to estimate the spin susceptibility of the InSb two-dimensional hole system. The g factor of the two-dimensional hole system decreases rapidly with increasing carrier density.
Gate-controlled phase switching in a parametron
Nosan, Ziga; Märki, Peter; Hauff, Nils; et al. (2019)
Physical Review E

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Peter Märki

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