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New structures and dynamics emerging from frustration

English title New structures and dynamics emerging from frustration
Applicant Tom Fennell
Number 182536
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Condensed Matter Physics
Start/End 01.12.2018 - 30.11.2022
Approved amount 934'867.00
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Keywords (7)

Magnetic excitations; Magnetic structures; Materials science; Spin ice; Spin liquid; Frustrated magnetism; Polarised and nonpolarised neutron scattering

Lay Summary (German)

Die Komponenten kondensierter Materie, wie Atome in einer Kristallstruktur oder magnetische Momente auf einem Gitter, interagieren miteinander. Gewöhnlich organisieren sie sich bei niedrigen Temperaturen in einem einzigen Zustand, in dem die Energie ihrer Wechselwirkungen minimiert wird. Wenn die Interaktionen frustriert sind, kann ein einzelner Zustand mit niedrigster Energie nicht realisiert werden und viele Zustände, die die Energie minimieren, sind möglich, was unkonventionelle Phänomene wahrscheinlich macht. Wir werden magnetische und strukturelle Fälle von "Frustration" auf der Suche nach qualitativ neuen Effekten untersuchen, die die Entwicklung neuer technologischer Materialien anregen könnten.
Lay summary

Streuexperimente mit Teilchen, wie Neutronen- oder Röntgenstreuung, bieten Zugang zu den Anordnungen (Korrelationen) und Fluktuationen (Dynamik) von Atomen und magnetischen Momenten in kondensierter Materie. In diesem Projekt werden wir neue magnetische Strukturen wie Skyrmionen untersuchen, die energetische Lösungen für das Problem frustrierter Wechselwirkungen sein können, und neue Arten von Strukturkorrelationen in Kristallen, bei denen die Atomstruktur frustriert ist (sog. Ladungseis). Wir werden auch die Stabilität von Anregungen in frustrierten Systemen untersuchen, da die Lebensdauer magnetischer und struktureller Fluktuationen durch die frustrierten Interaktionen qualitativ verändert werden kann. Materialien mit neuartigen Korrelationen und Dynamik sind für die Grundlagenforschung sehr interessant, um fundamentale Fragen in der Physik zu beantworten. Sie haben aber auch sehr hohes Potential für zukünftige Anwendungen z.B. in der Elektronik.

Direct link to Lay Summary Last update: 21.12.2018

Responsible applicant and co-applicants


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Associated projects

Number Title Start Funding scheme
162626 Frustration in Quantum and Classical Magnets 01.12.2015 Project funding (Div. I-III)
140862 Quantum Frustration in Model Magnets 01.07.2012 Project funding (Div. I-III)
160765 Mott Physics Beyond the Heisenberg Model in Iridates and Related Materials 01.01.2016 Sinergia
189644 Versatile high sensitivity and throughput magnetometer for quantum, functional and applied materials 01.03.2020 R'EQUIP
152734 Spin-liquid and spin-ice states in frustrated rare-earth and transition metal spinels 01.04.2014 SCOPES
150713 ZEBRA - a new neutron single-crystal diffractometer optimized for small samples and extreme conditions 01.11.2014 R'EQUIP
144972 High efficiency neutron spectrometer optimized for investigations under extreme conditions 01.01.2014 R'EQUIP


The concept of frustration is often associated with interactions in spin systems of particular geometry, and the formation of novel states such as spin ices or spin liquids. However, it is a general concept that may be applied to competing interactions amongst all manner of degrees of freedom, and which has identifiable and important consequences in the structures and dynamics of condensed matter. To continue our successful project on frustrated magnets that started in 2012 and renewed in 2015, we propose new directions in magnetic and structural frustration, and thorough studies of the consequences of competing interactions for both the formation of novel spin structures and the associated dynamics.Project A:Magnetic and structural frustration in fluoride pyrochlores: The transition metal fluoride pyrochlore CsNiCrF6 contains structural and magnetic Coulomb phases. We will establish a definitive model of the charge ice-type of correlated disorder in the crystal structure and investigate vibrational analogues of generalised Coulomb phase dynamics. We will study members of the series ANiCrF6 to isolate the role of the alkali metal ions, whose displacements resemble ‘rattlers’ in host-guest structures; and examine predictions of functionally important modified phonon propagation in ‘procrystalline’ materials. We propose to fully elucidate the spin Hamiltonian and magnetic dynamics of the magnetic Coulomb phase, which is a classical spin liquid, and extend our investigation to ultra-low temperatures where quantum fluctuations will become important.Project B:Quasiparticle transport and decay in frustrated magnets: Understanding the nature and fate of the elementary excitations in frustrated magnets is essential for the characterisation of their exotic fundamental properties and for their potential future exploitation in technological applications. We will study the propagation and decay of quasiparticles, spinwaves in triangular lattices with and without strong spin-lattice coupling, and extend these studies to materials where excitations may be topologically protected. We will perform the first experiments on thermal and especially magnon transport in such materials, in addition to neutron and X-ray spectroscopy.Project C:Magnetic frustration as a source of extended periodic spin textures: We will initiate the experimental study of quantum spin and spin-orbit liquids on the diamond lattice in MT2O4 (M=Cu, Ni, T=Rh, Al) spinels, and of two-dimensional correlated states on the triangular lattice in the NiGa2S4 family, aiming to discover new unconventional states and to inspect them as a source of topological spin textures. We will continue our work on the magnetic phases of MnSc2S4, where we have previously found a vortex lattice, to establish if a skyrmion crystal can be produced when applying the field in other symmetry directions. We will complete our current work on CdYb2Se4, a rare-earth based quantum antiferromagnet on the pyrochlore lattice.