Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 4: Spin structures and magnetic phase transitions

MA 4.11: Vortrag

Montag, 12. März 2018, 12:15–12:30, EB 202

Higgs mode and its decay in a two-dimensional antiferromagnet — Anil Jain^1,2, •Maximilian Krautloher¹, Juan Porras¹, Gihun Ryu¹, D.P. Chen¹, Douglas Abernathy³, Jitae Park⁴, Alexandre Ivanov⁵, Jiri Chaloupka⁶, Giniyat Khaliullin¹, Bernhard Keimer¹, and B.J. Kim^1,7 — ¹Max Planck Institute for Solid State Research, Stuttgart — ²Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai — ³Quantum Condensed Matter Division, ORNL — ⁴Heinz Maier-Leibnitz Zentrum, TU München — ⁵Institut Laue-Langevin, Grenoble — ⁶Central European Institute of Technology, Masaryk University, Kotlářská — ⁷Department of Physics, Pohang University of Science and Technology

In recent years significant research has focused upon emergent behavior arising from a convergence of spin-orbit coupling (SOC) and strongly correlated electron interaction energies in 4d and 5d-electron transition metal oxides. We have concentrated our investigation on Ca₂RuO₄, a layered 2D antiferromagnet. Mixing of the cubic crystal field and SOC results in a nominally non-magnetic pseudospin J=0 state, which contrasts with experimental findings. To resolve this issue G. Khaliullin (PRL 111, 197201 (2013)) proposed a mechanism where magnetically active transitions between the J=0 singlet and higher energy J=1 triplet are enabled by virtue of superexchange interactions, resulting in excitonic magnetic order. Here we present inelastic neutron scattering results that illustrate a key signature of this ground state – the presence of a longitudinal mode (or Higgs mode) that corresponds to length fluctuations of J.