Spin dynamics in the square-lattice cupola system Ba(TiO)Cu${}_4$(PO${}_4$)${}_4$

Abstract

We report high-resolution single-crystal inelastic neutron scattering measurements on the spin-1/2 antiferromagnet Ba(TiO)Cu${}_4$(PO${}_4$)${}_4$. This material is formed from layers of four-site \cupola" structures, oriented alternately upwards and downwards, which constitute a rather special realization of two-dimensional (2D) square-lattice magnetism. The strong Dzyaloshinskii-Moriya (DM) interaction within each cupola, or plaquette, unit has a geometry largely unexplored among the numerous studies of magnetic properties in 2D Heisenberg models with spin and spatial anisotropies. We have measured the magnetic excitations at zero field and in fields up to 5 T, finding a complex mode structure with multiple characteristic features that allow us to extract all the relevant magnetic interactions by modelling within the linear spin-wave approximation. We demonstrate that Ba(TiO)Cu${}_4$(PO${}_4$)${}_4$ is a checkerboard system with almost equal intra- and inter-plaquette couplings, in which the intra-plaquette DM interaction is instrumental both in enforcing robust magnetic order and in opening a large gap at the Brillouin-zone center. We place our observations in the perspective of generalized phase diagrams for spin-1/2 square-lattice models and materials, where exploring anisotropies and frustration as routes to quantum disorder remains a frontier research problem.

13 pages, 8 figures

References in corpus (15)

• Anomalous High-Energy Spin Excitations in La2CuO4
• Hall effect of triplons in a dimerized quantum magnet
• Quantum Spin Liquid in Spin 1/2 J1-J2 Heisenberg Model on Square Lattice: Many-Variable Variational Monte Carlo Study Combined with Quantum-Number Projections
• Hierarchical mean-field approach to the $J_1$-$J_2$ Heisenberg model on a square lattice
• Extension of the spin-1/2 frustrated square lattice model: the case of layered vanadium phosphates
• Evidence of Unconventional Universality Class in a Two-Dimensional Dimerized Quantum Heisenberg Model
• Evidence of quantum dimer excitations in Sr${}_3$Ir${}_2$O${}_7$
• Uniform and staggered magnetizations induced by Dzyaloshinskii-Moriya interactions in isolated and coupled spin 1/2 dimers in a magnetic field
• Magnetodielectric detection of magnetic quadrupole order in Ba(TiO)Cu${}_4$(PO${}_4$)${}_4$ with Cu${}_4$O${}_{12}$ square cupolas
• The frustrated Heisenberg antiferromagnet on the checkerboard lattice: the $J_1$--$J_2$ model
• Quantum Phase Transition in a Heisenberg Antiferromagnet on a Square Lattice with Strong Plaquette Interactions
• Magnetoelectric Behavior from $S=1/2$ Asymmetric Square Cupolas
• Magnetic structure of Ba(TiO)Cu${}_4$(PO${}_4$)${}_4$ probed using spherical neutron polarimetry
• Multiple magnon modes in spin-1/2 Heisenberg antiferromagnet on simple square lattice in strong magnetic field
• Magnetic structure in square cupola compound Ba(TiO)Cu${}_4$(PO${}_4$)${}_4$: a ${}^{31}$P NMR Study

Cited by in corpus (1)

• Microscopic Magnetism of A(TiO)Cu4(PO4)4 (A = Ba, Pb, Sr): 31P and 63,65Cu NMR Study