Field Dependence of Spin Waves in the Kondo Lattice CeCu₂

摘要

The Kondo lattice compound CeCu₂ shows an antiferromagnetic ordering below T_N = 3.5 K. The two moments in the primitive crystallographic unit cell are aligned antiparallel to each other and oriented along the orthorhombic c-axis even though the a-axis is the easy axis of magnetization. This can be explained by a strongly anisotropic antiferromagnetic exchange in the ac-plane which cancels out the crystal field anisotropy. The measurements of the spin wave dispersion at 1.5 K that we present in this paper for zero field and for 5 T in a-direction verify this assumption. Preliminary model calculations using the program package McPhase reproduce qualitatively the measured dispersion curves.