Excitation in Antiferromagnetic Quantum Spin Systems on the Triangular Lattice

抄録

Without assuming the classical ground state with a symmetry breaking, we derived spin wave excitation in the antiferromagnetic quantum spin systems on the triangular lattice. The motion of z-component spin is investigated to second order in the time derivative within the effective-field approximation. The spectrum of excitation is calculated by the use of Miyashita’s trial function. The obtained spin wave excitation has a phonon-like spectrum, which is similar to the spin-wave one based upon the classical ground state, although its velocity is modified.