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TT: Fachverband Tiefe Temperaturen
TT 80: Correlated Electrons: Poster
TT 80.29: Poster
Thursday, March 21, 2024, 15:00–18:00, Poster E
Unconventional magnetic excitation in novel frustrated spin-1/2 triangular antiferromagnets — •Fanjun Xu1,2, Bella Lake1,2, Nazmul Islam1, and Jan Embs3 — 1Helmholtz-Zentrum Berlin, DE — 2Technische Universität Berlin, DE — 3Paul Scherrer Institut, CH
In frustrated magnets, many exotic quantum phenomena can appear as a consequence of the competing interaction. One of the most celebrated examples is the highly degenerated ground state of unsatisfied spins on the triangular lattice antiferromagnet (TLAF). Theoretical studies suggest spin-1/2 TLAF develops long-range magnetic order at the ground state, combined with broadened and renormalized downward magnon excitations.
Surprisingly, a recent inelastic neutron scattering experiment on the spin-1/2 TLAF Ba3CoSb2O9 reveals unconventional multiband higher energy excitations. To clarify whether this unconventional higher energy excitation continuum is universal for spin-1/2 triangular antiferromagnets or not, an inelastic neutron scattering experiment on high-quality polycrystalline Ba3CoNb2O9 and Ba3CoTa2O9 was performed.
In this poster, the magnetic excitations of the novel spin-1/2 TLAF Ba3CoNb2O9 and Ba3CoTa2O9 will be presented. The strong quantum fluctuations of the effective S-1/2 cobalt moments are evident by the higher energy continuum qualitatively observed in both compounds. A Heisenberg model will be discussed with linear spin wave theory. Additionally, I will present a new empirical neutron spectroscopy sum rule that is specially tailored for frustrated magnets for the first time.
Keywords: Trianguler antiferromagnet; Quantum fluctuation; Unconventional magnetic excitation; Neutron scattering; Cobalt