Projects & Collaborations 20 foundShow per page10 10 20 50 Revealing 2D magnetism via nanoscale magnetometry Research Project | 4 Project MembersTwo-dimensional (2D) magnets have emerged as a new frontier in magnetism, both in terms of fundamental questions - including why such magnetism is stable at all - as well as from the device engineering point of view. In general, the stacking, twisting, and combining of van der Waals (vdW) materials with control down to individual atomic layers has started a revolution in heterostructure engineering. Layer-by-layer control offers a multitude of possible material combinations, without constraints imposed by lattice mismatch, along with the prospect of making compact devices, in which large electric fields can easily be applied. These new tools give researchers unprecedented control of interactions and band structure, as exemplified by the 2018 realization of superconducting twisted bilayer graphene. In the realm of magnetism, these methods can be used to tune the magnetic properties of a material or even to make materials, which are non-magnetic in the bulk, magnetic in 2D. Most importantly, both in view of understanding the physics of 2D magnetism and exploiting it for applications, vdW engineering may allow us to realize new and useful magnetic phases, which are only possible in 2D. In order to fully take advantage of these new developments, we must understand the role of anisotropy, disorder, inhomogeneity, and characteristic length-scales in 2D magnets and their heterostructures. Such investigations require sensitive local probes and techniques for measuring magnetism in small volumes. Our group, which has long worked at the forefront of sensitive magnetic imaging and torque magnetometry, is ideally positioned for such measurements. Here, we propose to apply our unique and highly sensitive tools to three types of measurements in 2D magnets: The characterization of static magnetism : determining the magnetic state and its dependence on the number of layers, anisotropy, as well as the presence of spatially modulated states, domains, defects, and inhomogeneities. The study of phase transitions and magnetic reversal : measuring the stability of magnetic phases, the nature of phase transitions, the process of magnetic reversal, and the role of domains and inhomogeneity therein. Understanding how to engineer 2D magnets : observing the effects of stacking, twisting, and applying electric fields to controllably induce phase transitions, magnetic reversal, magnetic texture, or new magnetic phases. The work of unravelling the mechanisms behind 2D magnetism is in its infancy. Given the inadequacy of conventional magnetic probes, we are convinced that our unique nanometer-scale magnetic field imaging and ultrasensitive torque magnetometry tools have much to contribute towards this effort. The results can be expected to have implications for 2D spintronic devices, 2D antiferromagnets, and the design of quantum materials via 2D vdW engineering in general. Ultra high precision electron beam lithography system for nanodevice and nanostructures definition Research Project | 6 Project MembersIn the last decades nano- and quantum-science have been steadily growing in large part also thanks to the availability of ever more advanced processing, manipulation, and imaging tech-niques. Specifically, nanofabrication has been the leading enabler of experiments and devices, in which quantum mechanics play a key role. The University of Basel is nationally and internationally recognized as a leader innanoscience and nanotechnology. It was the leading house of the National Center in Competence and Re-search (NCCR) on Nanoscience, which later became the Swiss Nanoscience Institute (SNI). The University of Basel is leading the NCCR SPIN for the realization of spin qubits in Silicon and is also co-leading the NCCR QSIT on Quantum Science and Technology (with ETHZ as Leading House). The present proposal to the SNF R'Equip scheme is a joint effort of six principal investigators (PIs) in the physics department of the University of Basel, who work on current topics in quantum- and nano-science. The PIs, who submit this proposal together, do research that relies on the availability of state-of-the-art fabrication tools, such as an electron beam lithography (EBL) system. The proposal makes the case for the purchase of an ultra-high precision EBL system that combines high resolution, tunable acceleration voltages, different write-field size, ultra-high precision alignment, proximity correction, and mechanical stability. This combination is unique and crucial for the University of Basel to stay at the forefront of nano-science and technology. The system will be installed in the new clean room shared between the University of Basel and the Department of Biosystem Science and Engineering of the ETH. Therefore, the purchased system will be available for the users of the clean-room. Scanning Nanowire Quantum Dot Research Project | 2 Project MembersIn this project we aim to combine the exceptional sensitivity of nanowire quantum dots as detectors of charge with scanning probe capabilities of customized cantilevers. The resulting scanning nanowire quantum dot will enable imaging of localized charges and electron densities with high sensitivity, high resolution, and under a large variety of environmental circumstances. FIBsuperProbes / Focused Ion Beam fabrication of superconducting scanning Probes Research Project | 3 Project MembersOur vision is to enable a new era in scanning probe microscopy (SPM), in which nanometer-scale sensing devices - specifically superconducting devices - can be directly patterned on-tip and used to reveal new types of contrast. To realize this vision, we will use focused ion beam (FIB) techniques to produce sensors with unprecedented size, functionality, and sensitivity directly on the tips of custom-designed cantilevers. The key to this undertaking will be the unique capability of FIB to mill, grow, or structurally modify materials - especially superconductors - at the nanometer-scale and on non-planar surfaces. Our FIB-fabricated probes will include on-tip nanometer-scale Josephson junctions (JJs) and superconducting quantum interference devices (SQUIDs) for mapping magnetic fields, magnetic susceptibility, electric currents, and dissipation. Crucially, the custom-built cantilevers, on which the sensors will be patterned, will enable nanometer-scale distance control, endowing our probes with exquisite spatial resolution and simultaneous topographic contrast. The resulting imaging techniques will significantly surpass state-of-the-art SPM and help us to unravel poorly understood phenomena in physics, chemistry, and material science, which are impossible to address with today's technology. High Performance Transmission Electron Microscope for Present and Future Nanomaterials Research Project | 9 Project MembersThe rise of nanoscience and nanotechnology would not have been happened without the impressive development of instruments that allow to resolve structure on the nanometer scale with atomic resolution. Examples are scanning-probe and electron microscopy techniques. In recent years, several major breakthroughs gave rise to an exceptional boost in the performance of today's electron microscopy (EM), both for solid-state and soft (e.g. biological) materials: 1) high-resolution through image corrections, 2) fast and highly efficient electron detectors, 3) efficient artifact-free sample fabrication (cryo-EM and FIBEM), and 4) 3D tomography and image reconstruction. This has given a leap to what can be imaged today, allowing for example to reconstruct the atomic structure of single proteins and image complex interfaces in solid-state materials with atomic scale. The University of Basel (UBAS) is nationally and internationally recognized as a leader in nanoscience and nanotechnology. It was the leading house of the National Center in Competence and Research (NCCR) on Nanoscience, which later became the Swiss Nanoscience Institute (SNI), the institution that submits the current proposal. UBAS is also co-leading the NCCR Molecular Systems Engineering and the NCCR QSIT on Quantum Science (both together with ETHZ). Nanoscience is a focus area in the research portfolio of UBAS and instrumental for the recent development of quantum science. The present proposal to the SNF R'Equip scheme has been put together by key researchers at UBAS who work on current topics in nanoscience and nanotechnology in various disciplines from quantum science, material science, polymer chemistry to molecular biology, and, who make use of EM available within the SNI. The principle investigators, who submit this proposal together, do research that relies on the availability of state-of-the-art nanoimaging tools, such as a transmission electron microscope (TEM). The proposal outlines a convincing case for the purchase of special, unique TEM that combines state-of-the-art (and fast) atomic resolution imaging with material analysis using EDX and scanning TEM (STEM). This combination is unique and crucial for the University of Basel to stay at the forefront of science. New Scanning Probes for Nanomagnetic Imaging Research Project | 1 Project MembersRecent years have seen rapid progress in nanometer-scale magnetic imaging technology, with scanning probe microscopy driving remarkable improvements in both sensitivity and resolution. Among the most successful tools are magnetic force microscopy (MFM), spin-polarized scanning tunneling microscopy, as well as scanning magnetometers based on nitrogen-vacancy centers in diamond, Hall-bars, and superconducting quantum interference devices (SQUIDs). Here, we propose the development and application of two particularly promising scanning probe techniques. The first is scanning SQUID microscopy, which - in its most advanced form - achieves record sensitivity to both stray magnetic flux and local thermal dissipation. Recently, it has been used to study the dynamics of superconducting vortices and to map nanometer-scale transport. In order to extend its applicability and optimize its functionality, we aim to realize a nanometer-scale SQUID integrated on an atomic force microscopy (AFM) tip, producing a hybrid AFM-SQUID sensitive to surface forces, stray magnetic flux, and local temperature. The second is based on newly developed nanowire (NW) force sensors, which have recently enabled a form of AFM capable of mapping both the size and direction of tip-sample forces. Using NWs functionalized with magnetic tips, we intend to realize a form of vectorial MFM capable of mapping stray magnetic fields with enhanced sensitivity and resolution compared to the state of the art. The unique capabilities of these two scanning probes will provide new types of imaging contrast for nanometer-scale magnetic structures such as domain walls , magnetic vortices , and magnetic skyrmions , whose equilibrium configurations and dynamical properties are crucial for both fundamental understanding and spintronic applications. In addition to studying magnetic nanostructures and spin-dependent phenomena, we will apply our newly developed techniques to the study of mesoscopic current flow in topological insulators and two-dimensional materials . Further target systems include superconducting films and nanostructures , in which our sensitive probes could help clarify the microscopic mechanisms of superconductivity. Ultrasensitive Force Microscopy and Cavity Optomechanics using Nanowire Cantilevers Research Project | 2 Project Membersp «Discovery and Nanoengineering of Novel Skyrmion-hosting Materials» Research Project | 2 Project MembersMagnetic Skyrmions are particle-like spin textures. They exhibit nanoscale dimensions and can be persistent due to topological protection. These nanoobjects have been first discovered at low temperatures in a small number of bulk single crystals of high purity and quality. Such chiral magnets are now of substantial interest for both fundamental condensed matter physics due to topological effects and applied sciences such as spintronics. The physics and manipulation of Skyrmions stabilized by Dzyaloshinskii-Moriya interaction (DMI) are relatively well established in bulk materials at low temperatures. The results promise novel device concepts in magnetic storage and information technology offering low power consumption. Technologically relevant structures will necessarily involve nanostructures operated at room temperature. The research on nanosystems is however mostly at the theoretical and numerical level because the relevant materials pose key challenges in the synthesis and fabrication of strain-free thin films that support the Skyrmion phase. Despite strong efforts, Skyrmions at room temperature have been observed only very recently in metallic ultrathin films and the bulk metallic alloy CoZnMn. Corresponding semiconductors and insulators that will decisively enhance the technological impact remain to be discovered.In this proposal we aim to go beyond the state-of-the-art of existing Skyrmionic schemes in that we intend to:-Systematically search for novel metallic, semiconducting, and insulating materials hosting Skyrmions at high temperatures-Achieve strain-free thin films and free-standing nanostructures with volume-DMI for Skyrmion-based devices -Image and manipulate Skyrmions up to the microwave frequency regime and down to the single Skyrmion level to set the base for Nanoskyrmionics.These ambitious goals can be achieved only by intimately combining different disciplines at their highest level and from diverse areas of research. In our proposal, we combine: computational materials discovery in condensed matter physics, chemical synthesis and molecular beam epitaxy, state-of-the-art neutron diffraction, nanotechnology and GHz spectroscopy. We propose to implement chemical precipitation from a solution as well as van der Waals epitaxy for strain-free thin film deposition. Direct correlation between the materials nature (structure, chemical composition, disorder configuration) and physical properties (magnetization, Skyrmion structure, dynamics) will be achieved by applying new computational and nanosensing techniques. The interdisciplinary efforts and results will lead to a paradigm-shift by providing a clear microscopic picture of the role and potential of Skyrmions in engineering, setting the stage for Skyrmionic science and technology at room temperature. Quantum sensing and imaging of spin textures in skyrmion materials Research Project | 1 Project Membersa A diamond quantum fibre pigtail Research Project | 2 Project MembersIndividual, optically active quantum systems form central building blocks for many attractive schemes in quantum communication and precision sensing. However, efficient photon extraction from these systems remains a major challenge, currently hindering the practical implementation of a variety of proposed applications in quantum sensing, communication and information processing. Efficient and robust optical interfacing of a single photon source or an optically active single spin is therefore highly desired and relevant to many emerging quantum technologies, which are currently pursued worldwide. 12 12
Revealing 2D magnetism via nanoscale magnetometry Research Project | 4 Project MembersTwo-dimensional (2D) magnets have emerged as a new frontier in magnetism, both in terms of fundamental questions - including why such magnetism is stable at all - as well as from the device engineering point of view. In general, the stacking, twisting, and combining of van der Waals (vdW) materials with control down to individual atomic layers has started a revolution in heterostructure engineering. Layer-by-layer control offers a multitude of possible material combinations, without constraints imposed by lattice mismatch, along with the prospect of making compact devices, in which large electric fields can easily be applied. These new tools give researchers unprecedented control of interactions and band structure, as exemplified by the 2018 realization of superconducting twisted bilayer graphene. In the realm of magnetism, these methods can be used to tune the magnetic properties of a material or even to make materials, which are non-magnetic in the bulk, magnetic in 2D. Most importantly, both in view of understanding the physics of 2D magnetism and exploiting it for applications, vdW engineering may allow us to realize new and useful magnetic phases, which are only possible in 2D. In order to fully take advantage of these new developments, we must understand the role of anisotropy, disorder, inhomogeneity, and characteristic length-scales in 2D magnets and their heterostructures. Such investigations require sensitive local probes and techniques for measuring magnetism in small volumes. Our group, which has long worked at the forefront of sensitive magnetic imaging and torque magnetometry, is ideally positioned for such measurements. Here, we propose to apply our unique and highly sensitive tools to three types of measurements in 2D magnets: The characterization of static magnetism : determining the magnetic state and its dependence on the number of layers, anisotropy, as well as the presence of spatially modulated states, domains, defects, and inhomogeneities. The study of phase transitions and magnetic reversal : measuring the stability of magnetic phases, the nature of phase transitions, the process of magnetic reversal, and the role of domains and inhomogeneity therein. Understanding how to engineer 2D magnets : observing the effects of stacking, twisting, and applying electric fields to controllably induce phase transitions, magnetic reversal, magnetic texture, or new magnetic phases. The work of unravelling the mechanisms behind 2D magnetism is in its infancy. Given the inadequacy of conventional magnetic probes, we are convinced that our unique nanometer-scale magnetic field imaging and ultrasensitive torque magnetometry tools have much to contribute towards this effort. The results can be expected to have implications for 2D spintronic devices, 2D antiferromagnets, and the design of quantum materials via 2D vdW engineering in general.
Ultra high precision electron beam lithography system for nanodevice and nanostructures definition Research Project | 6 Project MembersIn the last decades nano- and quantum-science have been steadily growing in large part also thanks to the availability of ever more advanced processing, manipulation, and imaging tech-niques. Specifically, nanofabrication has been the leading enabler of experiments and devices, in which quantum mechanics play a key role. The University of Basel is nationally and internationally recognized as a leader innanoscience and nanotechnology. It was the leading house of the National Center in Competence and Re-search (NCCR) on Nanoscience, which later became the Swiss Nanoscience Institute (SNI). The University of Basel is leading the NCCR SPIN for the realization of spin qubits in Silicon and is also co-leading the NCCR QSIT on Quantum Science and Technology (with ETHZ as Leading House). The present proposal to the SNF R'Equip scheme is a joint effort of six principal investigators (PIs) in the physics department of the University of Basel, who work on current topics in quantum- and nano-science. The PIs, who submit this proposal together, do research that relies on the availability of state-of-the-art fabrication tools, such as an electron beam lithography (EBL) system. The proposal makes the case for the purchase of an ultra-high precision EBL system that combines high resolution, tunable acceleration voltages, different write-field size, ultra-high precision alignment, proximity correction, and mechanical stability. This combination is unique and crucial for the University of Basel to stay at the forefront of nano-science and technology. The system will be installed in the new clean room shared between the University of Basel and the Department of Biosystem Science and Engineering of the ETH. Therefore, the purchased system will be available for the users of the clean-room.
Scanning Nanowire Quantum Dot Research Project | 2 Project MembersIn this project we aim to combine the exceptional sensitivity of nanowire quantum dots as detectors of charge with scanning probe capabilities of customized cantilevers. The resulting scanning nanowire quantum dot will enable imaging of localized charges and electron densities with high sensitivity, high resolution, and under a large variety of environmental circumstances.
FIBsuperProbes / Focused Ion Beam fabrication of superconducting scanning Probes Research Project | 3 Project MembersOur vision is to enable a new era in scanning probe microscopy (SPM), in which nanometer-scale sensing devices - specifically superconducting devices - can be directly patterned on-tip and used to reveal new types of contrast. To realize this vision, we will use focused ion beam (FIB) techniques to produce sensors with unprecedented size, functionality, and sensitivity directly on the tips of custom-designed cantilevers. The key to this undertaking will be the unique capability of FIB to mill, grow, or structurally modify materials - especially superconductors - at the nanometer-scale and on non-planar surfaces. Our FIB-fabricated probes will include on-tip nanometer-scale Josephson junctions (JJs) and superconducting quantum interference devices (SQUIDs) for mapping magnetic fields, magnetic susceptibility, electric currents, and dissipation. Crucially, the custom-built cantilevers, on which the sensors will be patterned, will enable nanometer-scale distance control, endowing our probes with exquisite spatial resolution and simultaneous topographic contrast. The resulting imaging techniques will significantly surpass state-of-the-art SPM and help us to unravel poorly understood phenomena in physics, chemistry, and material science, which are impossible to address with today's technology.
High Performance Transmission Electron Microscope for Present and Future Nanomaterials Research Project | 9 Project MembersThe rise of nanoscience and nanotechnology would not have been happened without the impressive development of instruments that allow to resolve structure on the nanometer scale with atomic resolution. Examples are scanning-probe and electron microscopy techniques. In recent years, several major breakthroughs gave rise to an exceptional boost in the performance of today's electron microscopy (EM), both for solid-state and soft (e.g. biological) materials: 1) high-resolution through image corrections, 2) fast and highly efficient electron detectors, 3) efficient artifact-free sample fabrication (cryo-EM and FIBEM), and 4) 3D tomography and image reconstruction. This has given a leap to what can be imaged today, allowing for example to reconstruct the atomic structure of single proteins and image complex interfaces in solid-state materials with atomic scale. The University of Basel (UBAS) is nationally and internationally recognized as a leader in nanoscience and nanotechnology. It was the leading house of the National Center in Competence and Research (NCCR) on Nanoscience, which later became the Swiss Nanoscience Institute (SNI), the institution that submits the current proposal. UBAS is also co-leading the NCCR Molecular Systems Engineering and the NCCR QSIT on Quantum Science (both together with ETHZ). Nanoscience is a focus area in the research portfolio of UBAS and instrumental for the recent development of quantum science. The present proposal to the SNF R'Equip scheme has been put together by key researchers at UBAS who work on current topics in nanoscience and nanotechnology in various disciplines from quantum science, material science, polymer chemistry to molecular biology, and, who make use of EM available within the SNI. The principle investigators, who submit this proposal together, do research that relies on the availability of state-of-the-art nanoimaging tools, such as a transmission electron microscope (TEM). The proposal outlines a convincing case for the purchase of special, unique TEM that combines state-of-the-art (and fast) atomic resolution imaging with material analysis using EDX and scanning TEM (STEM). This combination is unique and crucial for the University of Basel to stay at the forefront of science.
New Scanning Probes for Nanomagnetic Imaging Research Project | 1 Project MembersRecent years have seen rapid progress in nanometer-scale magnetic imaging technology, with scanning probe microscopy driving remarkable improvements in both sensitivity and resolution. Among the most successful tools are magnetic force microscopy (MFM), spin-polarized scanning tunneling microscopy, as well as scanning magnetometers based on nitrogen-vacancy centers in diamond, Hall-bars, and superconducting quantum interference devices (SQUIDs). Here, we propose the development and application of two particularly promising scanning probe techniques. The first is scanning SQUID microscopy, which - in its most advanced form - achieves record sensitivity to both stray magnetic flux and local thermal dissipation. Recently, it has been used to study the dynamics of superconducting vortices and to map nanometer-scale transport. In order to extend its applicability and optimize its functionality, we aim to realize a nanometer-scale SQUID integrated on an atomic force microscopy (AFM) tip, producing a hybrid AFM-SQUID sensitive to surface forces, stray magnetic flux, and local temperature. The second is based on newly developed nanowire (NW) force sensors, which have recently enabled a form of AFM capable of mapping both the size and direction of tip-sample forces. Using NWs functionalized with magnetic tips, we intend to realize a form of vectorial MFM capable of mapping stray magnetic fields with enhanced sensitivity and resolution compared to the state of the art. The unique capabilities of these two scanning probes will provide new types of imaging contrast for nanometer-scale magnetic structures such as domain walls , magnetic vortices , and magnetic skyrmions , whose equilibrium configurations and dynamical properties are crucial for both fundamental understanding and spintronic applications. In addition to studying magnetic nanostructures and spin-dependent phenomena, we will apply our newly developed techniques to the study of mesoscopic current flow in topological insulators and two-dimensional materials . Further target systems include superconducting films and nanostructures , in which our sensitive probes could help clarify the microscopic mechanisms of superconductivity.
Ultrasensitive Force Microscopy and Cavity Optomechanics using Nanowire Cantilevers Research Project | 2 Project Membersp
«Discovery and Nanoengineering of Novel Skyrmion-hosting Materials» Research Project | 2 Project MembersMagnetic Skyrmions are particle-like spin textures. They exhibit nanoscale dimensions and can be persistent due to topological protection. These nanoobjects have been first discovered at low temperatures in a small number of bulk single crystals of high purity and quality. Such chiral magnets are now of substantial interest for both fundamental condensed matter physics due to topological effects and applied sciences such as spintronics. The physics and manipulation of Skyrmions stabilized by Dzyaloshinskii-Moriya interaction (DMI) are relatively well established in bulk materials at low temperatures. The results promise novel device concepts in magnetic storage and information technology offering low power consumption. Technologically relevant structures will necessarily involve nanostructures operated at room temperature. The research on nanosystems is however mostly at the theoretical and numerical level because the relevant materials pose key challenges in the synthesis and fabrication of strain-free thin films that support the Skyrmion phase. Despite strong efforts, Skyrmions at room temperature have been observed only very recently in metallic ultrathin films and the bulk metallic alloy CoZnMn. Corresponding semiconductors and insulators that will decisively enhance the technological impact remain to be discovered.In this proposal we aim to go beyond the state-of-the-art of existing Skyrmionic schemes in that we intend to:-Systematically search for novel metallic, semiconducting, and insulating materials hosting Skyrmions at high temperatures-Achieve strain-free thin films and free-standing nanostructures with volume-DMI for Skyrmion-based devices -Image and manipulate Skyrmions up to the microwave frequency regime and down to the single Skyrmion level to set the base for Nanoskyrmionics.These ambitious goals can be achieved only by intimately combining different disciplines at their highest level and from diverse areas of research. In our proposal, we combine: computational materials discovery in condensed matter physics, chemical synthesis and molecular beam epitaxy, state-of-the-art neutron diffraction, nanotechnology and GHz spectroscopy. We propose to implement chemical precipitation from a solution as well as van der Waals epitaxy for strain-free thin film deposition. Direct correlation between the materials nature (structure, chemical composition, disorder configuration) and physical properties (magnetization, Skyrmion structure, dynamics) will be achieved by applying new computational and nanosensing techniques. The interdisciplinary efforts and results will lead to a paradigm-shift by providing a clear microscopic picture of the role and potential of Skyrmions in engineering, setting the stage for Skyrmionic science and technology at room temperature.
Quantum sensing and imaging of spin textures in skyrmion materials Research Project | 1 Project Membersa
A diamond quantum fibre pigtail Research Project | 2 Project MembersIndividual, optically active quantum systems form central building blocks for many attractive schemes in quantum communication and precision sensing. However, efficient photon extraction from these systems remains a major challenge, currently hindering the practical implementation of a variety of proposed applications in quantum sensing, communication and information processing. Efficient and robust optical interfacing of a single photon source or an optically active single spin is therefore highly desired and relevant to many emerging quantum technologies, which are currently pursued worldwide.
