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If you are looking for a  Semester and Master's Project, we have several to offer!

PhD in experimental condensed matter physics:
Exotic Phases and Excitations in Quantum Magnets

Conventional magnetic materials demonstrate long range spin order at low temperatures. There are numerous systems though,where quantum fluctuations destroy such order even at T=0. The most interesting of these are not the fully disordered ones, but those where quantum fluctuations stabilize some exotic, often “hidden” or topological order parameters. The best known example is the topological ground state in S=1 chains, for which F. D. M. Haldane won the 2016 Nobel Prize. In recent years, a dazzling variety of exotic phases have been predicted in quantum magnets with geometric frustration. Among these are gapped and gapless topological spin liquids, chiral and spin-nematic phases, spin density waves and resonating-bond states. Each such phase is also characterized by unique excitations that too are often topological in nature: Majorana quasiparticles, gauge fluxes, spinons, Higgs-like longitudinal modes, “magnetic monopoles”, etc. Also of interest are quantum phase transitions between different phases, and the role played by their coupling to the elastic crystal lattices. The race is on to find experimental realizations of the most interesting models and to investigate them in the laboratory.

Phase diagram of a J1-J2 frustrated square lattice quantum antiferromagnet. A magnetic field will extend the domain of the spin-nematic phase.  
Phase diagram of a J1-J2 frustrated square lattice quantum antiferromagnet. A magnetic field will extend the domain of the spin-nematic phase.
Multi-spinon excitations measured with neutron scattering in the Tomonaga-Luttinger spin liquid phase of the quantum magnet DIMPY.  
Multi-spinon excitations measured with neutron scattering in the Tomonaga-Luttinger spin liquid phase of the quantum magnet DIMPY.

The present PhD project at the Neutron Scattering and Magnetism Group, Laboratory for Solid State Physics, Physics Department, ETH Zurich, aims to apply state of the art experimental techniques to investigate exotic quantum phases and excitations in several carefully chosen frustrated magnetic compounds. As a first step, it will involve a detailed characterization of the novel materials using magnetometry, magneto-dielectric and magneto-thermodynamic measurements at mK-temperatures and high magnetic fields, as well as X-ray, muon spin rotation and neutron diffraction studies. The main thrust will be an extensive spectroscopic investigation. In-house ultra-high resolution Raman scattering will be performed under a range of conditions, including high-pressure diamond anvil experiments. Inelastic neutron scattering studies will be carried out at state of the art large-scale user facilities in Switzerland, France, UK, and the USA.

The successful candidate is expected to be actively involved in every phase of the project, and eventually take over a leading role in its realization. No prior experience in optical spectroscopy, muon spin rotation measurements or neutron scattering is required, but a solid background in laboratory work is indeed a must. Since the project is based around rather complex concepts in modern quantum solid state physics, a solid theoretical base in quantum mechanics, statistical physics and solid state physics is absolutely essential. Good computer skills are a plus. For ETH students, it is possible to start with a Masters project that may later develop into a PhD study.

For further information please contact Prof. Dr. Andrey Zheludev at .

 
 
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24.06.2017
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