Luo Yi, Marcus G G, Trump B A, Kindervater J, Stone M B, Rodriguez-Rivera J A, Qiu Yiming, McQueen T M, Tchernyshyov O, Broholm C
Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA.
Phys Rev B. 2020;101. doi: 10.1103/PhysRevB.101.144411.
We report a comprehensive neutron scattering study of low energy magnetic excitations in the breathing pyrochlore helimagnetic CuOSeO. Fully documenting the four lowest energy magnetic modes that leave the ferrimagnetic configuration of the "strong tetrahedra" intact ( meV), we find gapless quadratic dispersion at the point for energies above 0.2 meV, two doublets separated by 1.6(2) meV at the point, and a bounded continuum at the point. Our constrained rigid spin cluster model relates these features to Dzyaloshinskii-Moriya (DM) interactions and the incommensurate helical ground state. Combining conventional spin wave theory with a spin cluster form factor accurately reproduces the measured equal time structure factor through multiple Brillouin zones. An effective spin Hamiltonian describing complex anisotropic intercluster interactions is obtained.
我们报告了对呼吸型焦绿石螺旋磁体CuOSeO₃中低能磁激发的全面中子散射研究。我们充分记录了使“强四面体”的亚铁磁构型保持完整的四个最低能量磁模式（毫电子伏），发现在能量高于0.2毫电子伏时，Γ点处存在无隙二次色散，在M点处有两个间隔为1.6(2)毫电子伏的双重态，以及在X点处有一个有界连续区。我们的受限刚性自旋簇模型将这些特征与Dzyaloshinskii-Moriya（DM）相互作用和非公度螺旋基态联系起来。将传统自旋波理论与自旋簇形状因子相结合，通过多个布里渊区准确再现了测量的等时结构因子。得到了一个描述复杂各向异性簇间相互作用的有效自旋哈密顿量。
