Complete field-induced spectral response of the spin-1/2 triangular-lattice antiferromagnet CsYbSe2

Abstract

Fifty years after Anderson’s resonating valence-bond proposal, the spin-1/2 triangular-lattice Heisenberg antiferromagnet (TLHAF) remains the ultimate platform to explore highly entangled quantum spin states in proximity to magnetic order. Yb-based delafossites are ideal candidate TLHAF materials, which allow experimental access to the full range of applied in-plane magnetic fields. We perform a systematic neutron scattering study of CsYbSe2, first proving the Heisenberg character of the interactions and quantifying the second-neighbor coupling. We then measure the complex evolution of the excitation spectrum, finding extensive continuum features near the 120°-ordered state, throughout the 1/3-magnetization plateau and beyond this up to saturation. We perform cylinder matrix-product-state (MPS) calculations to obtain an unbiased numerical benchmark for the TLHAF and spectacular agreement with the experimental spectra. The measured and calculated longitudinal spectral functions reflect the role of multi-magnon bound and scattering states. These results provide valuable insight into unconventional field-induced spin excitations in frustrated quantum materials.

Triangular Lattice of Ho3+ with Seff = 1/2 in Antiferromagnetic KHoSe2

“…Contrastingly, in the presence of fields ranging from 3 to 5 T, CsYbSe 2 demonstrates a transition to sharp peaks characteristic of long-range ordering, which, at higher fields, revert to broad peaks. This transition in CsYbSe 2 is interpreted as a shift from 120° spin correlations to an up–up–down (UUD) configuration and eventually to a state where spins adopt a canted coplanar arrangement . Conversely, KHoSe 2 presents an inverse pattern: the presence of sharp features at 0 and 1 T may point to strong 120° spin correlations, while the subsequent smoothing of these peaks at higher fields may hint at a transition toward a coplanar state.…”

Coexistence of Long-Range Magnetic Order and Magnetic Frustration of a Novel Two-Dimensional S = 1/2 Structure: Na2Cu3(SeO3)4

“…This provides an alternate route to a quantum spin liquid state through the well-known resonating valence state proposed by Anderson as a potential explanation for high-temperature superconductivity [11]. Therefore, our main interest is to find 2D magnetic lattices built of S = 1/2 ions to enhance the quantum fluctuation and perform detailed theoretical and experimental investigations of their physical properties [11][12][13][14].…”

Angular‐Momentum Transfer Mediated by a Vibronic‐Bound‐State

“…14 members of this family have been identified to date. [ 21 , 22 , 23 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ] They all have planar triangular lattices decorated by antiferromagnetically coupled spins making them susceptible to geometric frustration, resulting in a lack of long‐range magnetic order down to the lowest probed temperatures. This family of candidate QSLs is objectively less defect prone than Yb(Mg, Ga)O 4 , [ 23 ] and the breadth of substitutional composites in the family makes it an ideal platform for the study and control of QSL excitations.…”