Evidence ofc(2×2)antiferromagnetic order of Mn in an ideal monolayer on Ag(001)
| Autor: | Y. Gauthier, Marie-Christine Hanf, Philippe Schieffer, G. Gewinner, C. Krembel |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Physical Review B. 62:2944-2955 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.62.2944 |
| Popis: | We present a dynamical low-energy electron diffraction analysis of the atomic and magnetic structure obtained by deposition of 0.9 Mn monolayers on Ag(001) held at 100 K. We find that the film grows in an essentially flat ideal monoatomic layer with the Mn located in fourfold hollow sites of the Ag(001) substrate that undergoes no sizeable reconstruction of its topmost layers. The Mn-Ag interlayer distance ${d}_{12}=2.00\ifmmode\pm\else\textpm\fi{}0.03\AA{}$ is found to be much larger than \ensuremath{\sim}1.85 \AA{} expected from simple addition of atomic radii in elemental \ensuremath{\alpha}-Mn and face-centered-cubic (fcc) Ag. This is direct evidence of the strong reduction in Mn $3d$ contribution to cohesion due to the atomiclike high-spin state of the Mn in the monolayer structure. Taking into account the exchange scattering by means of a local von Barth-Hedin exchange-correlation potential, we demonstrate that the weak intensity of the $c(2\ifmmode\times\else\texttimes\fi{}2)$ superstructure reflection intensities $I(E)$ observed at low energies only $(El~120\mathrm{eV})$ can be quite well explained in terms of a two-dimensional antiferromagnetic arrangement of the Mn moments. Nonmagnetic origins of these reflections such as out of plane (buckling) or in plane displacive reconstructions of the Mn monolayer as well as surface alloying with Ag or impurity related superstructures can be safely ruled out. Evidence of a $c(2\ifmmode\times\else\texttimes\fi{}2)$ antiferromagnetic to $p(1\ifmmode\times\else\texttimes\fi{}1)$ paramagnetic phase transition is also presented. |
| Databáze: | OpenAIRE |
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