A5026895705- Topological Materials and Phenomena
- Quantum and electron transport phenomena
- Graphene research and applications
- Quantum many-body systems
- Advanced Condensed Matter Physics
- Atomic and Subatomic Physics Research
- Magnetic Field Sensors Techniques
- Quantum Information and Cryptography
- Computational Physics and Python Applications
- Rare-earth and actinide compounds
- Magnetic properties of thin films
- 2D Materials and Applications
- Advanced Electrical Measurement Techniques
- Mechanical and Optical Resonators
- Physics of Superconductivity and Magnetism
- Surface and Thin Film Phenomena
- Scientific Research and Philosophical Inquiry
- Advancements in Semiconductor Devices and Circuit Design
University of Würzburg
2017-2025
A quantum anomalous Hall (QAH) insulator coupled to an s-wave superconductor is predicted harbor a topological superconducting phase, the elementary excitations of which (i.e. Majorana fermions) can form qubits upon non-Abelian braiding operations. recent transport experiment interprets half-quantized two-terminal conductance plateau as presence chiral fermions in millimeter-size QAH-Nb hybrid structure. However, there are concerns about this interpretation because non-Majorana mechanisms...
Evidence of axionic insulating behavior is shown in thin topological insulator films via analysis conductivity flow diagrams. As film thickness increases, the changes from a two-dimensional integer quantum Hall regime to one consistent with an axion insulator.
In the quantum anomalous Hall effect, edge states of a ferromagnetically doped topological insulator exhibit quantized resistance and dissipationless transport at zero magnetic field. Up to now, however, was experimentally assessed with standard measurement techniques which are difficult trace von-Klitzing constant R$_K$ high precision. Here, we present metrologically comprehensive measurement, including full uncertainty budget, quantization V-doped (Bi,Sb)$_2$Te$_3$ devices without external...
The quantum anomalous Hall effect in magnetic topological insulators has been recognized as a promising platform for applications metrology. primary reason this is the electronic conductance quantization at zero external field, which allows to combine it with standard of voltage. Here we demonstrate measurement scheme that increases robustness field resistor, allowing higher operational currents. This achieved by simultaneous current injection into two disconnected perimeters multi-terminal...
This study demonstrates that, contrary to earlier claims in the field involving analyses of a so-called ``zero Hall plateau'', it is more intricate than expected unambiguously reveal existence an axion insulator. In particular, authors find from their scaling analysis transport experiments on V-doped (Bi,Sb)${}_{2}$Te${}_{3}$ films varying thickness that truly three-dimensional bulk character necessary condition for insulators, likely not satisfied materials exhibiting zero plateau.
Abstract Achieving metrological precision of quantum anomalous Hall resistance quantization at zero magnetic field so far remains limited to temperatures the order 20 mK, while Curie temperature in involved material is as high K. The reason for this discrepancy one biggest open questions surrounding effect, and focus article. Here we show, through a careful analysis non-local voltages on multi-terminal Corbino geometry, that chiral edge channels continue exist without applied up bulk...
The quantum anomalous Hall effect (QAHE) in magnetic topological insulators offers great potential to revolutionize electrical metrology by establishing primary resistance standards operating at zero external field and realizing a universal "quantum toolbox" that can perform resistance, voltage current single instrument. To realize such promise, significant progress is still required address materials metrological challenges -- among which, one main challenge make the bulk of insulator...
The quantum anomalous Hall effect (QAHE) in magnetic topological insulators offers great potential to revolutionize electrical metrology by establishing primary resistance standards operating at zero external field and realizing a universal “quantum toolbox” that can perform resistance, voltage, current single instrument. To realize such promise, significant progress is still required address materials metrological challenges—among which, one main challenge make the bulk of insulator...
(Bi,Sb)${}_{2}$Te${}_{3}$ layers doped with Vanadium are ferromagnetic topological insulators exhibiting the quantum anomalous Hall effect (QAHE) at low temperatures. The resistivity is quantized to h/e${}^{2}$ without an external magnetic field. authors succeeded in reproducible epitaxial growth of thin layers, optimized Sb content a narrow range around 80% showing QAHE. Such grown on Si or InP substrates and protecting Te cap show quantization. QAHE persists independently interfaces...
Here we report the investigation of anomalous Hall effect in magnetically doped topological insulator (V,Bi,Sb)2Te3. We find it contains two contributions opposite sign. Both components are found to depend differently on carrier density, leading a sign inversion total as function applied gate voltage. The have different magnetization reversal fields, which combination with temperature dependent study points towards coexistence ferromagnetic orders system. Moreover, that response system...
The recent advent of topological states matter spawned many significant discoveries. quantum anomalous Hall (QAH) effect is a prime example due to its potential for applications in metrology, as well influence on fundamental research into the underlying and magnetic axion electrodynamics. Here, electronic transport studies (V,Bi,Sb)
The quantum anomalous Hall effect holds promise as a disruptive innovation in condensed matter physics and metrology, it gives access to resistance quantization terms of the von-Klitzing constant RK = h/e2 at zero external magnetic field. In this work, we study accuracy device based on topological insulator material (V,Bi,Sb)2Te3. We show that relative deviation from field is (4.4 +/- 8.7) nohm/ohm when extrapolated measurement current, (8.6 6.7) longitudinal resistivity (each with combined...
The search for topological superconductivity has motivated investigations into materials that combine and superconducting properties. half-Heusler compound YPtBi appears to be such a material; however, experiments have thus far been limited bulk single crystals, drastically limiting the scope of available experiments. This made it impossible investigate potential nature in this material. Experiments access details about state require sophisticated lithographic structures, typically based on...
Abstract The quantum anomalous Hall effect in magnetic topological insulators has potential for use resistance metrology applications. Electronic conductance is quantized to e 2 / h (where the elementary charge and Planck constant) due effect, which persists down zero external field compatible with standard of voltage. However, metrological applications are currently restricted by need low measurement currents temperatures. Here we report a scheme that increases robustness...
Macroscopic Quantum Tunneling The profound question of how the laws quantum mechanics merge into those governing classical physics at macroscopic sizes remains largely unexplored. In article number 2303165 by Kajetan M. Fijalkowski, Charles Gould, Laurens W. Molenkamp, and co-workers, tunneling magnetization, a phenomenon nature, is studied in magnetic object that is, without any doubt, macroscopic.
The importance of the Quantum Hall effect in metrological standards is well established, but its implementation many situations hindered by requirements a strong magnetic field. Recently, new material class, magnetically doped topological insulators, has been shown to exhibit an effect, dubbed Anomalous Effect, with completely novel physical origins and providing quantized plateau without needing This paper examines nature this particular focus on fact that axionic action term must be added...
The recent advent of topological states matter spawned many significant discoveries. quantum anomalous Hall effect[1-3] is a prime example due to its potential for applications in metrology[4, 5] as well influence on fundamental research into the underlying and magnetic states[6-11] axion electrodynamics[2, 12-14]. Here, we perform electronic transport studies (V,Bi,Sb)2Te3 ferromagnetic insulator nanostructure regime. This allows us access dynamics an individual domain. volume domain...
The search for topological superconductivity has motivated investigations into materials that combine and superconducting properties. half-Heusler compound YPtBi appears to be such a material, however experiments have thus far been limited bulk single crystals, drastically limiting the scope of available experiments. This made it impossible investigate potential nature in this material. Experiments access details about state require sophisticated lithographic structures, typically based on...