QENS study of tetrahedron dynamics in the ZnSc 1/1 approximant to the quasicrystal

Shibata, Kaoru  ; Yamada, Tsunetomo*; de Boissieu, M.*

We present a detailed study of Quasielastic Neutron Scattering (QENS) due to the tetrahedron dynamic among the order-disorder phase transition occurring at about Tc = 160 K. The QENS measurements have been performed at around Q = 2.67 [1/A] near the (1/2, 11/2, 2) superstructure reflection and for temperatures ranging from 100 K (i.e. below Tc) to 400 K. The QENS experiments were conducted on the DNA time-of-flight type Si analyzer near backscattering spectrometer installed at the MLF, J-PARC. The spectrometer was operated in high-resolution dE mode and at high momentum transfer Q mode, with an instrumental resolution of dE = 12 micro eV using Si311 analyzer. In the measured QENS spectrum, we observed two relaxation processes, not only the fast process which is characterized several 100 micro eV at the full width at FWHM, but also the slow process which is characterized several 10 micro eV at FWHM.