抄録
Parallel pumping and ferromagnetic resonance experiments in (C4H9NH3)2CuCl4 at 8.9 GHz and liquid helium temperatures show that in the magnetic field tilted away from the a- and b-axes the spin-wave spectrum splits into two branches and the width of the spin-wave band becomes narrow. These results are understood as follows: the spin-wave frequency of one ab-plane is different from those of the ab-planes immediately above and below because the interlayer exchange interaction is very weak and the adjacent layers are magnetically inequivalent and therefore the exchange and dipolar interactions of the transverse components of the spin precessions between adjacent layers vanish. Quantitative agreement between experiment and spin-wave theory is obtained. Accordingly it can be concluded that the spin-wave spectrum is indeed two-dimensional.
