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Projects / Programmes source: ARIS

Probing spin states near the surface of quantum spin materials

Research activity

Code Science Field Subfield
1.02.00  Natural sciences and mathematics  Physics   

Code Science Field
P260  Natural sciences and mathematics  Condensed matter: electronic structure, electrical, magnetic and optical properties, supraconductors, magnetic resonance, relaxation, spectroscopy 

Code Science Field
1.03  Natural Sciences  Physical sciences 
Keywords
magnetic resonance, quantum spin systems, superconductivity
Evaluation (rules)
source: COBISS
Researchers (9)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  14080  PhD Denis Arčon  Physics  Head  2018 - 2021  593 
2.  53742  Davor Grabnar    Technical associate  2021 
3.  18272  PhD Alan Gregorovič  Physics  Researcher  2018 - 2021  99 
4.  53022  PhD Rainer Oliver Kaltenbaek  Physics  Researcher  2019 - 2021  73 
5.  20209  PhD Martin Klanjšek  Physics  Researcher  2018 - 2021  193 
6.  09089  PhD Igor Muševič  Physics  Researcher  2018 - 2021  750 
7.  26465  PhD Matej Pregelj  Physics  Researcher  2018 - 2021  130 
8.  33800  Petra Šutar    Technical associate  2018 - 2020  66 
9.  21558  PhD Andrej Zorko  Physics  Researcher  2018 - 2021  290 
Organisations (2)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  90,038 
2.  1554  University of Ljubljana, Faculty of Mathematics and Physics  Ljubljana  1627007  33,822 
Abstract
This project will develop and implement advanced magnetic resonance probes and combine them with the high spatial resolution of microscopy in order to push the ultimate detection sensitivity to the limits necessary for investigations of the competing spin states in quantum-spin materials at a nanoscale of 10 nm. Quantum-spin materials with low-dimensional and geometrically frustrated lattices where not all interactions can be simultaneously satisfied are predicted to exhibit novel, highly non-trivial states of matter. They might also play a major role in future emerging quantum technologies such as entanglement-enhanced metrology or topological quantum computing. Their functionalities stem from the complexity of their phase diagrams, often embracing competing states, with several degrees of freedom (spin, charge, orbital and lattice) simultaneously active and entangled, all leading to a remarkable magnetic response on different time and length scales. Regions in the phase diagrams where nanoscale inhomogeneities, i.e., spin texturing with the modulations of the spin structure on a scale of several tens of nm driven by geometrical frustration or doping with magnetic and non-magnetic impurities, are an important manifestation of such complexity and require advanced theoretical concepts and experimental techniques that often go beyond the available state-of-the-art methods. Due to the low sensitivity of conventional magnetic resonance techniques, which require samples with )1015 spins, quantum-spin materials with such nanoscale inhomogeneities cannot be satisfactorily characterised. This drawback also makes any prospects of addressing and manipulating quantum-spin systems exceedingly demanding. The project team, with a well-established track record in the research of quantum-spin materials and instrumentation development, has recently identified two promising geometrically frustrated systems, i.e., the frustrated spin chain compound β-TeVO4 and the layered triangular lattice of 1T-TaS2. The spin inhomogeneities develop at a scale of ~10 nm, due to the formation of spin stripe texturing in β-TeVO4 or when (non)magnetic impurities embedded into 1T-TaS2 challenge the robustness of its quantum-spin liquid. In order to investigate the static and dynamic properties of these two model compounds, we propose cutting-edge technologies based on magnetic resonance, but with the ability to assign the signal to a specific surface site with a precision of about 10 nm. The detection of electron paramagnetic resonance signals at the surfaces of quantum-spin materials with custom-designed microstrip resonators fabricated from the superconducting materials, the use of low-energy surface muons in the muon spin relaxation studies, the detection of magnetic resonance signals at cryogenic temperatures with magnetic force detection or by the use diamond nitrogen vacancy magnetometry will improve the sensitivity to probe 104 spins. By developing, comparing, and integrating these four different surface-sensitive platforms, the breakthrough will be a controlled experimental emulation of fundamental model Hamiltonians for frustrated quantum-spin materials when they develop spin inhomogeneities at the nanoscale. This will result in the characterization of their phase diagrams, targeting fundamental features such as quantum-spin liquids, global topological order, and fractional excitations. By achieving the improved sensitivity of magnetic resonance by more than 10 orders of magnitude, the project’s ground-breaking contribution will provide crucial novel insights into the physics of many-body quantum systems with essential elements of complexity. Moreover, it will also foster new directions in research when novel quantum physical phenomena are limited to the surface (topological insulators, Dirac (and also their three-dimensional analogues Weyl) semi-metals, etc.).
Significance for science
At the level of EU, the initiative for the second quantum revolution has been set with the Quantum Manifesto document [http://qurope.eu/system/files/u567/Quantum%20Manifesto.pdf ] and within H2020 programs EU has endorsed quantum technologies as one of the priorities in 21st century. It is thus generally accepted within the scientific community that quantum technologies are currently one of the fastest developing scientific disciplines. Here we propose an ambitious research project, which is at the cutting edge of today's quantum spin materials and quantum detection science and we address several questions, which may have profound impact in the future: 1.) Studies of quantum spin materials, when local inhomogeneities perturb the ground state. This is an extremely important field of research, because in such cases new states of matter may develop. This project will focus on frustrated spin systems – the most fertile ground for the development of new concepts, finding new model systems with potential applications. By studying carefully selected model systems, we will systematically follow on the nanometric scale how QSL is destroyed and then replaced by another unconventional state (e.g., superconducting state). This has never been tried before by merging the high energy resolution of magnetic resonance and the high spatial resolution of microscopy. Next, the dynamics of spin stripe phases (or spin textures in general) has not yet been studied, although it is of general importance to understand the formation of such enigmatic phase and to predict where to search for it in the future. Thus, the answers to these questions will push the limits of our knowledge in the selected directions, and open new scientific and technological pathways in future quantum spin materials. 2.) Novel methods in the magnetic resonance detection: The main drawback of current(conventional) magnetic resonance techniques is their sensitivity. Despite being local probe techniques, their applications at the nanoscale have been limited. This project proposes innovative approaches that tackle this issue. To our knowledge, there is no report in the literature where diamond NV magnetometry is applied together with the cryogenic positioning system to detect magnetic resonance signal at low temperatures. The advances in this instrumentation development will be of particular importance – they could be applied to the broad range of problems in correlated electron systems with complex phase diagrams. Moreover, the instrumentation development in the direction of single spin detection at the cryogenic temperatures may be the first step towards emerging quantum technologies. Therefore, besides providing crucial insights in the physics of complex quantum spin systems, it will be a foundational step in the realization of single spin detection and the large-scale architectures for topologically protected quantum computation and information.
Significance for the country
At the level of EU, the initiative for the second quantum revolution has been set with the Quantum Manifesto document [http://qurope.eu/system/files/u567/Quantum%20Manifesto.pdf ] and within H2020 programs EU has endorsed quantum technologies as one of the priorities in 21st century. It is thus generally accepted within the scientific community that quantum technologies are currently one of the fastest developing scientific disciplines. Here we propose an ambitious research project, which is at the cutting edge of today's quantum spin materials and quantum detection science and we address several questions, which may have profound impact in the future: 1.) Studies of quantum spin materials, when local inhomogeneities perturb the ground state. This is an extremely important field of research, because in such cases new states of matter may develop. This project will focus on frustrated spin systems – the most fertile ground for the development of new concepts, finding new model systems with potential applications. By studying carefully selected model systems, we will systematically follow on the nanometric scale how QSL is destroyed and then replaced by another unconventional state (e.g., superconducting state). This has never been tried before by merging the high energy resolution of magnetic resonance and the high spatial resolution of microscopy. Next, the dynamics of spin stripe phases (or spin textures in general) has not yet been studied, although it is of general importance to understand the formation of such enigmatic phase and to predict where to search for it in the future. Thus, the answers to these questions will push the limits of our knowledge in the selected directions, and open new scientific and technological pathways in future quantum spin materials. 2.) Novel methods in the magnetic resonance detection: The main drawback of current(conventional) magnetic resonance techniques is their sensitivity. Despite being local probe techniques, their applications at the nanoscale have been limited. This project proposes innovative approaches that tackle this issue. To our knowledge, there is no report in the literature where diamond NV magnetometry is applied together with the cryogenic positioning system to detect magnetic resonance signal at low temperatures. The advances in this instrumentation development will be of particular importance – they could be applied to the broad range of problems in correlated electron systems with complex phase diagrams. Moreover, the instrumentation development in the direction of single spin detection at the cryogenic temperatures may be the first step towards emerging quantum technologies. Therefore, besides providing crucial insights in the physics of complex quantum spin systems, it will be a foundational step in the realization of single spin detection and the large-scale architectures for topologically protected quantum computation and information.
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