Spin-density wave dynamics in a 2D distorted triangular lattice antiferromagnet

Insulating spin systems on distorted triangular lattices represent a point of contact between the 1D physics of spin chains and that of 2D frustrated triangular magnets. Quantum fluctuations in these systems stabilize exotic phases in applied magnetic field, like 1/3 plateaux and incommensurate spin-density waves (SDW). The latter has been recently observed in 1D chains, but it is predicted to survive in particular 2D distorted lattices. However, experimental realizations in 2D systems still lack. Moreover, the dynamics of these states in 2D remain unclear. Cs2CoBr4 allows to tackle these questions experimentally. Neutron diffraction revealed the presence of 1/3 magnetization plateau and an incommensurate SDW in its phase diagram. We also succeeded in growing large single crystals. Therefore, Cs2CoBr4 offers the unique possibility to study SDW dynamics in a 2D distorted lattice system.