MRI: Development of a Cryogenic Integrated Micro-Raman-Brillouin-Mandelstam Spectrometer

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Nontechnical Description:This major research instrumentation (MRI) development project aims to build an integrated micro-Raman-Brillouin-Mandelstam spectrometer system with a capability for samples held at cryogenic temperatures. Raman scattering and Brillouin-Mandelstam scattering are inelastic light scattering processes, which are used to measure energies of various types of elemental excitations, such as phonons and magnons, in solid materials. Phonons are quanta of crystal lattice vibrations, which are associated with sound velocities of solids and also reveal themselves in electrical, thermal and optical phenomena in materials. Magnons are quanta of electron spin waves, which determine characteristics of magnetic materials. The capability of conducting measurements at low temperatures is particularly important for studying magnetic materials. The spectral range and design of the spectrometer allow for its use for samples of small dimensions and thicknesses. The project provides an impetus to development of the Brillouin spectroscopy instrumentation, and its elevation to the level currently enjoyed by Raman spectroscopy. Information obtained with the spectroscopy system facilitates synthesis and characterization of new materials, and helps in better understanding of their properties. The instrument increases research competitiveness and enhances science and engineering education at the University of California - Riverside, which is an accredited Hispanic Serving Institution. Technical Description:The characteristics of the micro-Raman-Brillouin-Mandelstam spectrometer system make it a multi-user facility, and enable science and engineering researchers from universities and industry to conduct studies in a wide range of topics: from the cutting-edge fundamental solid-state physics of magnons, phonons and non-trivial topological states to engineering measurements of the elastic constants of composites. The advanced features of the system include (i) a specially designed rotating microscopy stage and imaging system for measuring the energy dispersion of phonons, magnons, and other elemental excitations in the temperature range from 4 K to 700 K; (ii) a high spatial resolution for the samples with the atomic thickness, lateral dimensions approximately 250 nanometers for magnons and about 1 micrometer for phonons; (iii) a modulus for recording phonon and magnon energies substantially below the current 1-GHz limit of conventional spectrometers; and (iv) a stage for simultaneous excitation and observation of coherent phonons and magnons with high spatial and temporal resolution. The possibility of investigating atomically-thin films with lateral dimensions in the micrometer range allows researchers to measure acoustic phonon energy dispersion. The capabilities of the system provide fundamental knowledge of phonons and magnons in two-dimensional and one-dimensional materials; the strength of the magnon-phonon and spin-lattice interactions in magnetic materials; elastic constants, phonon velocities and Gruneisen parameters in low-dimensional materials; charge density waves in quantum materials; as well as characteristics of other quasiparticles in novel materials, heterostructures and biological systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.