Neutron scattering study of yttrium iron garnet

作者：Shamoto Shin ichi^*; Ito Takashi U; Onishi Hiroaki; Yamauchi Hiroki; Inamura Yasuhiro; Matsuura Masato; Akatsu Mitsuhiro; Kodama Katsuaki; Nakao Akiko; Moyoshi Taketo; Munakata Koji; Ohhara Takashi; Nakamura Mitsutaka; Ohira Kawamura Seiko; Nemoto Yuichi; Shibata Kaoru

来源：Physical Review B, 2018, 97(5): 054429.

DOI：10.1103/PhysRevB.97.054429

The nuclear and magnetic structure and full magnon dispersions of yttrium iron garnet Y3Fe5O12 have been studied using neutron scattering. The refined nuclear structure is distorted to a trigonal space group of R (3) over bar. The highest-energy dispersion extends up to 86 meV. The observed dispersions are reproduced by a simple model with three nearest-neighbor-exchange integrals between 16a (octahedral) and 24d (tetrahedral) sites, J(aa), J(ad), and J(dd), which are estimated to be 0.00 +/- 0.05, -2.90 +/- 0.07, and -0.35 +/- 0.08 meV, respectively. The lowest-energy dispersion below 14 meV exhibits a quadratic dispersion as expected from ferromagnetic magnons. The imaginary part of q-integrated dynamical spin susceptibility chi ''(E) exhibits a square-root energy dependence at low energies. The magnon density of state is estimated from chi ''(E) obtained on an absolute scale. The value is consistent with the single chirality mode for the magnon branch expected theoretically.

• 出版日期2018-2-26