Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 48: Spin Dynamics and Transport: Spin Excitations and Spin Torque Phenomena
MA 48.14: Vortrag
Donnerstag, 23. März 2017, 13:00–13:15, HSZ 101
Quasi-one dimensional spin chains and unconventional magnetic excitations in YbAlO3 — •Stanislav Nikitin1, Liusuo Wu2, Leonid Vasylechko3, and Andrey Podlesnyak2 — 1Max Planck Institute for Chemical Physics of Solids, Dresden, 01187, Germany — 2Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA — 3Lviv Polytechnic National University, Lviv, 79000, Ukraine
The low-energy spin dynamics of Yb3+ in YbAlO3 have been studied using inelastic neutron scattering. We observe that Yb3+ moments form weakly coupled spin chains running along the c-axis without any significant magnetic interactions within the ab plane. CEF effect leads to large splitting of the Yb3+ multiplet J=7/2 and the magnetic properties at low temperatures are always dominated by the lowest-energy doublet, which can be described as pseudo spin S=1/2, and the effective Lange g-factor. Excitation spectrum of YbAlO3 above the ordering temperature TN=0.9 K, precisely represents a gapless multispinon continuum as was predicted for a S=1/2 Heisenberg chain. Below TN the gap Δ=0.3 meV appears and the spectrum splits into the single-particle mode and two-particle continuum. Of particular relevance for the present results are also our previous investigations of YbFeO3. In this compound Yb3+ moments forms similar magnetic chains but magnetic excitations are highly modified by a strong Fe-Yb interaction. Our results represent a rather rare case of quantum spin dynamics in 4f based systems and provide an experimental basis for future studies of low-dimensional magnets.