Dimensional reduction and incommensurate dynamic correlations in the $$S=\frac{1}{2}$$ triangular-lattice antiferromagnet Ca3ReO5Cl2

The observation of spinon excitations in the $$S=\frac{1}{2}$$ triangular antiferromagnet Ca3ReO5Cl2 reveals a quasi-one-dimensional (1D) nature of magnetic correlations, in spite of the nominally 2D magnetic structure. This phenomenon is known as frustration-induced dimensional reduction. Here, we present high-field electron spin resonance spectroscopy and magnetization studies of Ca3ReO5Cl2, allowing us not only to refine spin-Hamiltonian parameters, but also to investigate peculiarities of its low-energy spin dynamics. We argue that the presence of the uniform Dzyaloshinskii-Moriya interaction (DMI) shifts the spinon continuum in momentum space and, as a result, opens a zero-field gap at the Γ point. We observed this gap directly. The shift is found to be consistent with the structural modulation in the ordered state, suggesting this material as a perfect model triangular-lattice system, where a pure DMI-spiral ground state can be realized. Frustration-induced dimensional reduction is manifested in lower dimensionality of magnetic correlations compared to that of the magnetic structure. Here the authors demonstrate the role of the uniform Dzyaloshinskii-Moriya interaction in the recently synthesized material Ca3ReO5Cl2 exhibiting dimensional reduction.