Thin film MnGe grown on Si(111)

Abstract

MnGe has been grown as a thin film on Si(111) substrates by molecular beam epitaxy. A 10 Å layer of MnSi was used as the seed layer in order to establish the B20 crystal structure. Films of a thickness between 45 and 135 Å have been prepared and structurally characterized using reflection high-energy electron diffraction, atomic force microscopy and x-ray diffraction. These studies provided evidence that MnGe forms in the cubic B20 crystal structure as islands exhibit a very smooth surface. The islands become larger with increasing film thickness. A magnetic characterization reveals that the ordering temperature of MnGe thin films is enhanced compared to that for bulk material. The properties of the helical magnetic structure obtained from magnetization and magnetoresistivity measurements are compared with those of films of the related compound MnSi. The much stronger Dzyaloshinskii-Moriya interaction in MnGe results in a higher rigidity of the spin helix.

Chiral skyrmions in cubic helimagnet films: The role of uniaxial anisotropy

“…Recently, the challenge of creating and observing such textures was overcome by the fabrication of free-standing nano-layers of cubic helimagnets 25 and the synthesis of epitaxial thin films of these materials on Si(111) substrates. 24,[26][27][28][29][30][31] Despite numerous indirect indications of skyrmionic states in different nonlinear systems 32,33 confined cubic helimagnets still remain the only class of materials where skyrmionic states can be induced, observed, and manipulated in a broad range of the thermodynamical parameters. 25,28,29,34,35 Investigations of chiral skyrmions in cubic helimagnet nano-layers have gained importance after the discovery of similar skyrmionic states stabilized by surface/interface DM interactions in nano-layers of common magnetic metals 36,37 and perspectives of their applications in data storage technologies.…”

Hall effect and transmission electron microscopy of epitaxial MnSi thin films

“…We present Hall effect data in section III with an interpretation that is consistent with measurements of both thin films and bulk crystals. This has important implications not only for other B20 epilayers, including FeGe/Si(111) 20,33 , Fe 1−x Co x Si/Si(111) 25,34,35 and Mn 1−x Fe x Si/Si(111) 36 and MnGe/Si(111) 37 , but for bulk chiral magnets as well. In section IV we present calculations of the magnetic contrast produced in TEM images of skyrmions in thin films under optimal image conditions.…”

Atomic-scale visualization of topological spin textures in the chiral magnet MnGe

“…MBE growth: A series of 10-500 nm thick MnGe(111) films were grown via molecular beam epitaxy on (P-doped, n-type) Si(111) substrates (26,27), which were treated with a buffered HF solution to remove the native oxide layer and H-terminate the surface. The freshly prepared Si(111) substrates were moved immediately into the UHV growth chamber to prevent re-oxidation, and annealed at ~800 °C until the 7x7 RHEED pattern characteristic of clean Si(111) emerged.…”

“…To understand the structure of domain walls (DWs) and their intersections, we chose initial configurations with specific textures, and relaxed the energy. To compare with SP-STM data, we look at the surface manifestation of textures whose energetics is governed by ℋ. MBE growth: A series of 10-500 nm thick MnGe(111) films were grown via molecular beam epitaxy on (P-doped, n-type) Si(111) substrates (26,27), which were treated with a buffered HF solution to remove the native oxide layer and H-terminate the surface. The freshly prepared Si(111) substrates were moved immediately into the UHV growth chamber to prevent re-oxidation, and annealed at ~800 °C until the 7x7 RHEED pattern characteristic of clean Si(111) emerged.…”