Spin texture induced by nonmagnetic doping and spin dynamics in 2D triangular lattice antiferromagnet h-Y(Mn,Al)O3

In many geometrically frustrated magnets, a weak perturbation can potentially induce new competing ground states. In particular, novel effects induced by defects in frustrated magnets represent a highly nontrivial and interesting problem. Here, we demonstrate that a non-magnetic impurity can produce an extended spin structure (spin texture) in h-YMnO3, a triangular lattice antiferromagnet with non-collinear magnetic order. Using inelastic neutron scattering (INS), we measured the full spin-wave spectra of Al-doped h-YMnO3, which revealed the presence of magnon damping with clear momentum dependence. Our model calculation incorporating the spin texture well describes the INS data, which supports the formation of spin textures. Our study provides the first experimental confirmation of the impurity-induced spin textures. It provides new insights and understanding of the impurity effects in a wide variety of non-collinear magnetic systems.