Evolution of Spinons with Magnetic Field in the One-Dimensional Heavy Fermion Yb 2 Pt 2 Pb

摘要: The antiferromagnetic (AF) metal Yb 2 Pt 2 Pb has a layered crystal structure, with Yb ions arranged in chains along the c-axis, while pairs of chains form orthogonal dimers in the tetragonal a-b plane, an in-plane structure that is topologically equivalent to the Shastry-Sutherland lattice (SSL). In zero magnetic field, 70% of the magnetic spectral weight is static, consisting of AF Bragg peaks corresponding to moments that order at T N= 2. 07 K, while fluctuations of the Yb moments, present even at T= 0 are responsible for the remaining 30%. The low energy magnetic excitation spectrum observed in neutron scattering experiments is unambiguously one-dimensional, consisting exclusively of gapped, Heisenberg-like spinons that disperse along the Yb chain direction, while remaining dispersionless in the SSL layers. As field is increased, the static magnetic order is suppressed and a rapidly evolving set of longitudinal …