Neutron Scattering for Condensed Matter Studies

About the course:The short-range strong interaction of neutron with matter and the inherent magnetic moment of neutron, makes neutron scattering a unique probe in condensed matter research. An important advantage of neutrons is that they carry no charge and can penetrate the bulk of materials. They interact via strong force with the nuclei of the material and the scattering cross section varies randomly between various elements and even between two isotopes of the same element. This allows one to observe light atoms such as hydrogen in the presence of heavier ones and distinguish neighbouring elements in the periodic table easily. Notably, hydrogen and deuterium have large contrast with respect to neutrons. One can exploit isotopic substitution and contrast variation methods in such studies. Since neutron also carries a magnetic moment of -1.91?N, it also interacts with magnetic moment in atoms, making it a unique probe for determination of microscopic magnetic structure. Wavelength and energy of thermal neutron match with the lattice spacing and excitations in condensed matter and makes it an indispensable tool to study both structure and dynamics in condensed matter. Using neutronscattering techniques with varying momentum transfer and energy transfer range and resolution one is capable or understanding structure and dynamics in materials at various length and time scales.PRE-REQUISITES: M.Sc in Physics or Chemistry/bachelor’s in Material Science. The course is a stand-alone course for application of neutron scattering to condensed matter problems.INTENDED AUDIENCE: Ph. D. students and researchers in condensed matter physicsINDUSTRY SUPPORT:Some characterization tools like Diffraction, SANS and PNR are often used by industry

Week 1: Properties of neutron, Comparison with other probes: optical rays, x-rays, electrons, Nature of interaction between neutrons and matter at microscopic length scale Week 2:Neutron Sources: Reactors and Accelerator based sources, Neutron Scattering Instrumentation for condensed matter studies vis a vis neutron sources, Neutron detectors. Week 3:Principles of Neutron Scattering under Born approximation, Scattering Laws, coherent and incoherent scattering, Principle of detailed balance, correlation functions. Week 4:Neutron diffraction at different length scales: microscopic to mesoscopic. Week 5:Neutron diffraction from powders, single crystals, liquid and amorphous systems Week 6:Magnetic structure using neutron diffraction Week 7:Small Angle Neutron Scattering (SANS) from precipitates and inhomogeneities Week 8:Polarized Neutron Reflectometry (PNR) from magnetic thin films Week 9:Back to Born approximation and scattering law. Inelastic and Quasi-elastic neutron scattering for dynamics in condensed matter. Week 10:Inelastic neutron scattering from phonons. Experiments to determine phonon dispersion relations using single crystals and phonon density of states from powders. Magnons. Week 11:Quasi-elastic neutron scattering to determine stochastic dynamics like diffusion in solids and liquids Week 12:Detailed discussion on available neutron sources and spectrometers at nuclear reactors and spallation neutron sources for experiment design with examples.