$(C_2{H}_5{\mathrm{NH}}_3{)}_2{\mathrm{CuCl}}_4$: A Physical System for the Experimental Investigation of Intrinsic Localized Modes

The weak dissipation of spin waves in magnetic materials makes antiferromagnets realistic candidates for the experimental observation of intrinsic localized modes. Our molecular dynamics simulations with different antiferromagnets reveal that the lowest lying uniform spin wave mode of the antiferromagnet $({\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{NH}}_3{)}_2{\mathrm{CuCl}}_4$ is unstable and that it can be driven sufficiently hard with a 1 Oe cw microwave field to generate intrinsic localized spin wave modes.