Spin superfluid state at room temperature

The spin superfluid state was observed in Yttrium Iron Garnet (YIG) at room temperature. It is similar to a Homoge- neous Precessing State (HPD), observed early in antiferromagnetic superfluid 3He-B. The difference between magnon BEC state and spin superfluidity is discussed. The conditions for long distance coherent magnetization transport are highlighted. We explain, why spin superflow is not possible in the case of attractive interaction between magnons, like in in-plain magnetized YIG film.