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Projects / Programmes source: ARIS

Novel experimental approach for determination of quantum spin liquids

Research activity

Code Science Field Subfield
1.02.01  Natural sciences and mathematics  Physics  Physics of condesed matter 

Code Science Field
1.03  Natural Sciences  Physical sciences 
Keywords
quantum materials, spin liquids, geometrical frustration, kagome spin lattice, Kondo effect
Evaluation (rules)
source: COBISS
Researchers (8)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  53450  Tina Arh  Physics  Junior researcher  2020 - 2023  35 
2.  36353  PhD Matjaž Gomilšek  Physics  Researcher  2021 - 2023  91 
3.  39140  PhD Nejc Janša  Physics  Junior researcher  2020 - 2021  12 
4.  20209  PhD Martin Klanjšek  Physics  Researcher  2020 - 2023  193 
5.  00400  PhD Dušan Ponikvar  Physics  Researcher  2021  127 
6.  26465  PhD Matej Pregelj  Physics  Researcher  2020 - 2023  130 
7.  18274  PhD Polona Umek  Chemistry  Researcher  2020 - 2023  326 
8.  21558  PhD Andrej Zorko  Physics  Head  2020 - 2023  290 
Organisations (1)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  90,038 
Abstract
Background and rationale: Quantum spin liquids (QSLs) represent an intriguing state of matter, where quantum entanglement plays a decisive role. These states are endorsed by geometrical frustration and remain magnetically disordered even at zero temperature. They feature unconventional magnetic excitations known as spinons, which behave as quasiparticles with complex interactions and statistics, making QSLs potentially useful for quantum computation. A number of QSL states, which differ by spinon dispersion, can be stabilized by different perturbations to the nearest-neighbor Heisenberg exchange Hamiltonian. The relevant perturbations include structural disorder, interactions with further neighbors and magnetic anisotropy. However, due to their complexity and difficult experimental determination, these states are very purely understood. Objectives and specific aims: The main objective of the proposed project is to provide the first experimental approach for microscopic determination of QSLs that will allow clear distinction between various possible states. We suggest a novel method, which uses impurities as in-situ probes of the host QSL state, an approach that is well-established in superconductors. We will exploit a spinon Kondo effect, which we have recently discovered and can be effectively detected by muons spin rotation (mSR). The focus will be on the quantum kagome antiferromagnetic model (KAFM), being a promising platform of the QSL states. Indeed, a theoretical consensus about the QSL ground state of this model has already been reached, yet, its true nature remains controversial. Both, states with zero or finite gap to the lowest-lying excitation have been theoretically proposed, but never conclusively confirmed by experiment. A specific aim of our study is to determine how different perturbations affect the selection of the QSL ground state of three most promising KAFM materials with seemingly fundamentally different spinon properties. Methods to be used: To reach the project goals, various complementary expertise in experimental and theoretical physics and in chemistry are essential. Our team, therefore, consists of experts in sensitive local-probe magnetic techniques, state-of-the-art numerical calculations and advanced sample synthesis routes. The project leader has had a long record in the field of frustrated magnetism. Since 2008, he has published several top-level papers (4 Nat. Phys, 2 Nat. Commun., 10 PRL), the majority of them (1 Nat. Phys, 1 Nat. Commun., 7 PRL) as the corresponding author. This experience will provide the backbone for the planned activities, which include mSR, nuclear magnetic resonance (NMR) and electron spin resonance (ESR) experiments, numerical renormalization group, finite temperature Lanczos and density-functional theory calculations, and hydrothermal sample syntheses. These will be performed at the Jožef Stefan Institute (IJS), with the exception of more specific experiments, like mSR and experiments under extreme conditions (NMR and ESR at high fields and low temperatures) which will be performed in specialized partner laboratories at the Paul Scherrer Institute, Université Paris-Sud 11 and the National High Magnetic Field Laboratory. Expected results and impact for the field: Our systematic study will overcome the pending issue of reliable QSL determination by providing a new local-probe-based approach. Furthermore, it will address the most fundamental questions related to various perturbations that are intrinsically present in KAFM materials. Our project will thus provide the foundations for understanding the enigmatic QSLs. The developed methodology will allow characterization of QSLs beyond the KAFM model. The knowledge about QSLs may also help explaining other intriguing quantum phenomena, like high-Tc superconductivity. Moreover, understanding the stability of QSLs and ways of their manipulation could be highly relevant for development of new quantum technologies.
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