The magnonic superfluid droplet at room temperature

Abstract

We declare the observation of spin superfluid state in Yttrium Iron Garnet (YIG) at room temperature. It is similar to a Homogeneous Precessing State (HPD), observed earlier in antiferromagnetic superfluid $^3$He-B. The formation of this state explains by the repulsive interaction between magnons, which is required as a prior condition for the spin superfluidity. It establishes an energy gap, which stabilizes the long range superfluid transport of magnetization and determines the Ginzburg-Landau coherence length. This discovery paves a way to many quantum applications of supermagnonics at room temperature, such as magnetic Josephson effect, long distance spin transport, Q-bit, quantum logics, magnetic sensors and others.