MAGNETIZATION AND MAGNON EXCITATION ENERGIES OF THE MAGNETIC SEMICONDUCTOR EuTe

Abstract

We present analytic expressions for the temperature dependent magnetization and magnon dispersion relation of the antiferromagnetic (AFM) EuTe . This bulk semiconductor represent a concentrated spin system for which the interaction between magnons has to be taken into account. We do this using the renormalized spin wave theory. A higher order Green's function according to Tjablikov is used for their description. As a result, we obtain a modified Bloch-T3/2 law, for low temperatures and high magnetic fields. A full analytic expression is given for the sublattice magnetization of the AFM EuTe (B0 = 0), with a Néel temperature of TN = 9.81 K. In the case of EuTe , the magnon excitation energies exhibit a characteristic maximum. For q = 0, an energy gap Eg occurs in the spin wave spectrum, a consequence of the AFM exchange interaction J2(T). Such energy gaps exist in the spectrum of magnon excitation energies only in systems with AFM interactions.