Magnetic susceptibility of EuTe/PbTe Heisenberg antiferromagnetic superlattices: Experimental and theoretical studies

Abstract

We report results on the temperature dependence of the susceptibilities of a set of MBE-grown short-period EuTe/PbTe antiferromagnetic superlattices having different EuTe layer thicknesses. In-plane and orthogonal susceptibilities have been measured and display a strong anisotropy at low temperature, confirming the occurrence of a magnetic phase transition in the thicker samples, as seen also in neutron diffraction studies. We suggest that dipolar interactions stabilize antiferromagnetic long-range order in an otherwise isotropic system and we present numerical and analytical results for the low- §

Ferromagnetic transition in EuS-PbS multilayers

“…13,[22][23][24][25][26] Until now, the properties of antiferromagnetic/nonmagnetic EuTe-PbTe structures have been studied, for which an interlayer coupling, 6,27 a decrease of Néel temperature with decreasing EuTe layer thickness, 28 and anisotropy effects [28][29][30][31] were found. A ferromagnetic/ nonmagnetic multilayer system of EuS intercalated with insulating SrS has been studied as well.…”

Theoretical studies of model thin EuTe films with surface elastic stresses

“…Moreover, for the thin¯lm [8] the biquadratic interaction parameter A has been found, and in [9] the dipolar contribution has been calculated. The elastic energy term is introduced here for the¯rst time.…”

“…The fourth term in (1) stands for the Zeeman interaction, where h = ¡ g· B H z , with g being the gyromagnetic factor, · B -Bohr magneton, and H z -external magnetic¯eld applied along the z-direction (in thē lm plane). The¯fth term in Hamiltonian (1) describes the long-range dipolar interactions within the¸-th plane only [9]. Regarding these interactions, it has been shown in [9] that the contribution to the dipolar energy originating from the interplanar interactions is much smaller than that from the interplanar ones, and thus it can be neglected.…”

“…The¯fth term in Hamiltonian (1) describes the long-range dipolar interactions within the¸-th plane only [9]. Regarding these interactions, it has been shown in [9] that the contribution to the dipolar energy originating from the interplanar interactions is much smaller than that from the interplanar ones, and thus it can be neglected. Finally, the last term in eq.…”

“…where the summation is performed over all lattice sites in a given (111) plane [9]. The expression (5) for the Gibbs energy satis¯es the equilibrium conditions:…”