Squeezed thermal spin states of magnons in the ferromagnet

In this paper, we discuss squeezed thermal spin states of magnons that are described by the Heisenberg Hamiltonian in the ferromagnet, in which the magnon system possesses a new kind of quasiparticle, which we call ferromagnon, i.e. a “dressed” quasi-particle obtained from the magnons by a Bogoliubov-Valatin transformation . Generally, the mass and noise properties of ferromagnons possess potentially important and novel effects in condensed matter physics, which have extensive application in the fields of science and technology. Moreover, it is convenient to introduce the Holstein-Primakoff method, in order to take into account the nonlinear interaction among spin waves. At last we describe the quantum fluctuations of spin-components in the squeezed thermal spin states of magnons and their temperature-dependence. Below some temperature, the squeezed thermal spin states of ferromagnons show squeeze effect.