arXiv subjects

Marcin Kisiel

Publications and source records attributed to Marcin Kisiel.

7 recordsLinked to original sources

arXiv2026

Mechanical detection of sub-band mobilities of two-dimensional electron gas on reduced SrTiO$_3$(001) surface

The two-dimensional electron gas (2DEG) in reduced strontium titanate offers a versatile platform for oxide electronics, yet its dissipation mechanisms under field driven charge fluctuations remain poorly understood. Here, we combine low-temperature atomic force microscopy with scanning tunnelling spectroscopy to probe the force and dissipation responses of a mechanical oscillator interacting with the STO 2DEG. The observation of Rydberg like image potential states by tunnelling experiments confirm the 2DEG formation, while dissipation spectroscopy reveals bias-dependent peaks linked to local electrostatic gating and charge redistribution within the 2DEG energy sub-bands. These features are quantitatively explained by variations in quantum capacitance as carrier density is tuned by electric fields. Under magnetic fields, dissipation peaks obey the Kohler's rule, allowing extraction of carrier mobilities in each sub-band. Our results establish a non-invasive AFM - based methodology for quantifying energy losses in quantum oxides, providing new insights into charge dynamics relevant for spintronic applications.

cond-mat.mtrl-sci↗

arXiv2022

Energy dissipation from confined states in nanoporous molecular networks

Crystalline nanoporous molecular networks are assembled on the Ag(111) surface, where the pores confine electrons originating from the surface state of the metal. Depending on the pore sizes and their coupling, an antibonding level is shifted upwards by 0.1 to 0.3 eV as measured by scanning tunneling microscopy. On molecular sites, a down-shifted bonding state is observed, which is occupied under equilibrium conditions. Low-temperature force spectroscopy reveals energy dissipation peaks and jumps of frequency shifts at bias voltages, which are related to the confined states. The dissipation maps show delocalization on the supra-molecular assembly and a weak distance-dependence of the dissipation peaks. These observations indicate that two-dimensional arrays of coupled quantum dots are formed, which are quantitatively characterized by their quantum capacitances and resonant tunneling rates. Our work provides a method for studying the capacitive and dissipative response of quantum materials with nanomechanical oscillators.

cond-mat.mtrl-sci↗

arXiv2019

Joule meets van der Waals: Mechanical dissipation via image potential states on a topological insulator surface

Dissipation mechanisms are experimentally studied on topological insulator surfaces of Bi2Te3, where common Joule dissipation was observed to be suppressed due to topologically protected surface states. Thus, a novel type of dissipation mechanism is observed by pendulum AFM, which is related to single electron tunneling resonances into image potential states that are slightly above the Bi2Te3 surface. The application of a magnetic field leads to the break down of the topological protection of the surface states and restores the expected Joule dissipation process. Nanomechanical energy dissipation experienced by the cantilever of pendulum AFM provides a novel source of information on the dissipative nature of the quantum-tunneling phenomena on the topological insulator surface.

cond-mat.mes-hall↗

arXiv2019

Characterization of Hydrogen Plasma Defined Graphene Edges

We investigate the quality of hydrogen plasma defined graphene edges by Raman spectroscopy, atomic resolution AFM and low temperature electronic transport measurements. The exposure of graphite samples to a remote hydrogen plasma leads to the formation of hexagonal shaped etch pits, reflecting the anisotropy of the etch. Atomic resolution AFM reveals that the sides of these hexagons are oriented along the zigzag direction of the graphite crystal lattice and the absence of the D-peak in the Raman spectrum indicates that the edges are high quality zigzag edges. In a second step of the experiment, we investigate hexagon edges created in single layer graphene on hexagonal boron nitride and find a substantial D-peak intensity. Polarization dependent Raman measurements reveal that hydrogen plasma defined edges consist of a mixture of zigzag and armchair segments. Furthermore, electronic transport measurements were performed on hydrogen plasma defined graphene nanoribbons which indicate a high quality of the bulk but a relatively low edge quality, in agreement with the Raman data. These findings are supported by tight-binding transport simulations. Hence, further optimization of the hydrogen plasma etching technique is required to obtain pure crystalline graphene edges.

cond-mat.mes-hall↗

arXiv2018

Mechanical dissipation from charge and spin transitions in oxygen deficient SrTiO_3

Bodies in relative motion separated by a gap of a few nanometers can experience a tiny friction force. This non-contact dissipation can have various origins and can be successfully measured by a sensitive pendulum atomic force microscope tip oscillating laterally above the surface. Here, we report on the observation of dissipation peaks at selected voltage-dependent tip-surface distances for oxygen-deficient strontium titanate (SrTiO_3) surface at low temperatures (T = 5K). The observed dissipation peaks are attributed to tip-induced charge and spin state transitions in quantum-dot-like entities formed by single oxygen vacancies (and clusters thereof, possibly through a collective mechanism) at the SrTiO_3 surface, which in view of technological and fundamental research relevance of the material opens important avenues for further studies and applications.

cond-mat.str-el↗

arXiv2016

CDW slips and giant frictional dissipation peaks at the NbSe$_2$ surface

Accessing, controlling and understanding nanoscale friction and dissipation is a crucial issue in nanotechnology, where moving elements are central. Recently, ultra-sensitive noncontact pendulum Atomic Force Microscope (AFM) succeeded in detecting the electronic friction drop caused by the onset of superconductivity in Nb, raising hopes that a wider variety of mechanisms of mechanical dissipation arising from electron organization into different collective phenomena will become accessible through this unconventional surface probe. Among them, the driven phase dynamics of charge-density-waves (CDWs) represents an outstanding challenge as a source of dissipation. Here we report a striking multiplet of AFM dissipation peaks arising at nanometer distances above the surface of NbSe$_2$ - a layered compound exhibiting an incommensurate CDW. Each peak appears at a well defined tip-surface interaction force of the order of a nN, and persists until T=70K where CDW short-range order is known to disappear. A theoretical model is presented showing that the peaks are connected to tip-induced local 2$π$ CDW phase slips. Under the attractive potential of the approaching tip, the local CDW surface phase landscape deforms continuously until a series of 2$π$ jumps occur between different values of the local phase. As the tip oscillates to and fro, each slip gives rise to a hysteresis cycle, appearing at a selected distance, the dissipation corresponding to "pumping" in and out a local slip in the surface CDW phase of NbSe$_2$.

cond-mat.mes-hall↗

arXiv2015

Probing Atomic Structure and Majorana Wavefunctions in Mono-Atomic Fe-chains on Superconducting Pb-Surface

Motivated by the striking promise of quantum computation, Majorana bound states (MBSs) in solid-state systems have attracted wide attention in recent years. In particular, the wavefunction localization of MBSs is a key feature and crucial for their future implementation as qubits. Here, we investigate the spatial and electronic characteristics of topological superconducting chains of iron atoms on the surface of Pb(110) by combining scanning tunneling microscopy (STM) and atomic force microscopy (AFM). We demonstrate that the Fe chains are mono-atomic, structured in a linear fashion, and exhibit zero-bias conductance peaks at their ends which we interprete as signature for a Majorana bound state. Spatially resolved conductance maps of the atomic chains reveal that the MBSs are well localized at the chain ends (below 25 nm), with two localization lengths as predicted by theory. Our observation lends strong support to use MBSs in Fe chains as qubits for quantum computing devices.

physics.atm-clus↗