Observation of the spiral spin liquid in a triangular-lattice material

TL;DR

This paper reports the experimental observation of a spiral spin liquid state in a triangular-lattice material, confirmed through neutron scattering and simulations, advancing understanding of frustrated magnetism.

Contribution

First experimental identification of the spiral spin liquid in a real material, demonstrating its realization in AgCrSe2 and linking it to theoretical models.

Findings

Observation of SSL in AgCrSe2 via neutron scattering

Close realization of the Heisenberg J1-J2-J3 model

Exotic magnetic states driven by thermal fluctuations and frustration

Abstract

The spiral spin liquid (SSL) is a highly degenerate state characterized by a continuous contour or surface in reciprocal space spanned by a spiral propagation vector. Although the SSL state has been predicted in a number of various theoretical models, very few materials are so far experimentally identified to host such a state. Via combined single-crystal wide-angle and small-angle neutron scattering, we report observation of the SSL in the quasi-two-dimensional delafossite AgCrSe$_2$. We show that it is a very close realization of the ideal Heisenberg $J_1$--$J_2$--$J_3$ frustrated model on the triangular lattice. By supplementing our experimental results with microscopic spin-dynamics simulations, we demonstrate how such exotic magnetic states are driven by thermal fluctuations and exchange frustration.