Synchrotron X-rays could improve commercial permanent magnets

Scientists at the U.S. Department of Energy's Argonne National Laboratory have recently unearthed new clues to making magnets longer lasting and more powerful through element-specific X-ray magnetic circular dichroism (XMCD) measurements. They have analyzed magnetic moment reversal at each of two inequivalent Nd sites (g and f sites) in a tetragonal single crystal of Nd₂Fe₁₄B, which is currently known to be the strongest permanent magnet. The results provide clear evidence that intrinsic magnetic stability has its atomic origins predominantly at Nd g sites, which exhibit a strong preference for c-axis alignment at ambient temperature and dictate the macroscopic easy-axis direction. Chemical substitution at Nd f sites, which undermines stability by favoring the xy plane, could enhance intrinsic coercivity. For more information, contact Catherine Foster (+1-630-252-5580, cfoster@anl.gov) at Argonne, and also see the paper, "Atomic Origin of Magnetocrystalline Anisotropy in Nd₂Fe₁₄B", D. Haskel et al., Phys. Rev. Lett., 95, 217207 (2005).