Spin-density-wave magnetism in layered chromium studied by perturbed-angular-correlation spectroscopy

Results obtained by perturbed-angular-correlation (PAC) spectroscopy on epitaxial chromium thin films are compared with data obtained from the same samples by neutron-diffraction experiments. We report on the study of a 250-nm-thick Cr single layer and an Fe/Cr multilayer with Cr thickness of 25 nm grown on ${\mathrm{N}\mathrm{b}/\mathrm{A}\mathrm{l}}_2{\mathrm{O}}_3$ (11̱02). The chromium single layer film orders below the Néel temperature as a longitudinal $\left({\mathrm{AF}}_2\right)$ spin density wave antiferromagnet with the spins out of plane, while the Cr in the Fe/Cr multilayer orders as a transversal $\left({\mathrm{AF}}_1\right)$ spin density wave antiferromagnet with the spins in plane. In addition we observe a minority volume fraction in a commensurate ${\mathrm{AF}}_0$ phase, stable up to at least 400 K. The present results prove that PAC probes the intrinsic magnetic features of chromium and therefore validate this technique as a complementary approach towards the understanding of the chromium magnetism in thin films and Fe/Cr multilayers.