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TT: Fachverband Tiefe Temperaturen
TT 9: Correlated Magnetism – Low-Dimensional Systems
TT 9.11: Talk
Monday, March 17, 2025, 17:45–18:00, H33
Modelling low-energy spin excitation measurements in field-induced phases of the spin-ladder antiferromagnet BiCu2PO6 — Patrick Pilch1, Kirill Amelin2, •Gary Schmiedinghoff3, Anneke Reinold1, Changqing Zhu1, Kirill Yu. Povarov4, Sergei Zvyagin4, Hans Engelkamp5, Yin-Ping Lan6, Guo-Jiun Shu6, Fang-Cheng Chou7, Urmas Nagel2, Toomas Rõõm2, Götz S. Uhrig1, Benedikt Fauseweh1,3, and Zhe Wang1 — 1TU Dortmund, 44227 Dortmund, Germany — 2NICPB, 12618 Tallinn, Estonia — 3DLR, 51147 Cologne, Germany — 4HZDR, 01328 Dresden, Germany — 5Radboud University, 6525 ED Nijmegen, The Netherlands — 6Taipei Tech, Taipei 10608, Taiwan — 7NTU, Taipei 10617, Taiwan
We report on terahertz spectroscopic measurements and subsequent theoretical modelling of quantum spin dynamics on single crystals of a spin-1/2 frustrated spin-ladder antiferromagnet BiCu2PO6 as a function of applied external magnetic fields. Anisotropic spin triplon excitations are observed, which split in applied magnetic fields with a quantum phase transition at Bc1 = 21.4 T for fields applied along the crystallographic a axis.
We theoretically model the magnetic field dependence of the triplon modes by using continuous unitary transformations to determine an effective low energy Hamiltonian. Through an exhaustive parameter search we find numerically optimized parameters to very well describe the experimentally observed modes, which corroborate the importance of significant magnetic anisotropy in the system.
The talk focuses on the theoretical analysis of the experimental data.
Keywords: Coupled Spin Ladders; Triplon; Terahertz Spectroscopy; Flow Equation; Continuous Unitary Transformation