LNS: Laboratory for Neutron Scattering and ImagingThe Laboratory for Neutron Scattering and Imaging (LNS) at the Paul Scherrer Institute is responsible for the scientific exploitation, operation and development of neutron scattering and imaging instruments at the Swiss Spallation Neutron Source (SINQ). The team of 50 senior scientists, postdoctoral researchers and PhD students further collaborates on diverse research projects ranging from modern topics in condensed matter physics and materials science to pressing questions in energy research and health care. read more
PhD, Master, Bachelor or Semester projects at the LNSWe offer students the possibility to do their PhD or educational research in our lab. See Teaching and Education for detailed information on Master/Diploma thesis, Bachelor/Semester work and practical courses at the LNS. Currently we have open positions for
- Semester projects on several topics
- Master project - Elastic properties in low dimensional quantum systems
- Master project - Discovery of new Skyrmion lattice materials
- Master project - Spontaneous magnon decay in non-collinear antiferromagnets
- Master project - Geometrical magnetic frustration beyond insulating ionic compounds
- Master project - Magnetic order in anisotropic triangular materials
- Master project - Magnetic structure of the quantum trimer compound Cs3Cu3Cl8OH
27. March 2017
Tuning the multiferroic mechanisms of TbMnO3 by epitaxial strainK. Shimamoto, S. Mukherjee et al., Scientific Reports 7, 44753 (2017). A current challenge in the field of magnetoelectric multiferroics is to identify systems that allow a controlled tuning of states displaying distinct magnetoelectric responses. Here we show that the multiferroic ground state of the archetypal multiferroic TbMnO3 is dramatically modified by epitaxial strain. Neutron diffraction reveals that in highly strained films the magnetic order changes from the bulk-like incommensurate bc-cycloidal structure to commensurate magnetic order. Concomitant with the modification of the magnetic ground state, optical second-harmonic generation (SHG) and electric measurements show an enormous increase of the ferroelectric polarization, and a change in its direction from along the c- to the a-axis. Our results suggest that the drastic change of multiferroic properties results from a switch of the spin-current magnetoelectric coupling in bulk TbMnO3 to symmetric magnetostriction in epitaxially-strained TbMnO3. These findings experimentally demonstrate that epitaxial strain can be used to control single-phase spin-driven multiferroic states.
17. March 2017
Sub-pixel correlation length neutron imaging: Spatially resolved scattering information of microstructures on a macroscopic scaleR.P. Harti et al., Scientific Reports 7, 44588 (2017). Neutron imaging and scattering give data of significantly different nature and traditional methods leave a gap of accessible structure sizes at around 10 micrometers. Only in recent years overlap in the probed size ranges could be achieved by independent application of high resolution scattering and imaging methods, however without providing full structural information when microstructures vary on a macroscopic scale. In this study we show how quantitative neutron dark-field imaging with a novel experimental approach provides both sub-pixel resolution with respect to microscopic correlation lengths and imaging of macroscopic variations of the microstructure. Thus it provides combined information on multiple length scales. A dispersion of micrometer sized polystyrene colloids was chosen as a model system to study gravity induced crystallisation of microspheres on a macro scale, including the identification of ordered as well as unordered phases. Our results pave the way to study heterogeneous systems locally in a previously impossible manner.
20. February 2017
Magnetic Field Dependence of Excitations Near Spin-Orbital Quantum CriticalityA. Biffin et al., Physical Review Letters 118, 067205 (2017). The spinel FeSc2S4 has been proposed to realize a near-critical spin-orbital singlet (SOS) state, where entangled spin and orbital moments fluctuate in a global singlet state on the verge of spin and orbital order. Here we report powder inelastic neutron scattering measurements that observe the full bandwidth of magnetic excitations and we find that spin-orbital triplon excitations of an SOS state can capture well key aspects of the spectrum in both zero and applied magnetic fields up to 8.5 T. The observed shift of low-energy spectral weight to higher energies upon increasing applied field is naturally explained by the entangled spin-orbital character of the magnetic states, a behavior that is in strong contrast to spin-only singlet ground state systems, where the spin gap decreases upon increasing applied field.
8. February 2017