Quasi-Two Dimensional Spin and Phonon Excitations in High Tc related Quantum Magnets

          @misc{ pirsa_PIRSA:15040165,
            doi = {10.48660/15040165},
            url = {https://pirsa.org/15040165},
            author = {Gaulin, Bruce},
            keywords = {Condensed Matter},
            language = {en},
            title = {Quasi-Two Dimensional Spin and Phonon Excitations in High Tc related Quantum Magnets},
            publisher = {Perimeter Institute},
            year = {2015},
            month = {apr},
            note = {PIRSA:15040165 see, \url{https://pirsa.org}}
          }
          

Abstract

New developments in time-of-flight neutron spectroscopy allow a remarkably comprehensive determination of the full spin and phonon excitation spectrum in many materials. I will discuss these new techniques and show results from the "214" family of layered quantum magnets - which are also the La(2-x)Ba/Sr(x)CuO4 high Tc superconductors. We observe the expected highly dispersive spin excitations emanating from the "pi-pi" magnetic zone centres, as well as a host of optic and acoustic phonons, and roughly speaking, the spin and phonon excitations separate as a function of momentum. However, a very interesting resonant phenomena is observed which is coincident with the low energy crossings of the dispersive spin excitations with the relatively dispersion less phonons.