GaAs–Fe₃Si Core–Shell Nanowires: Nanobar Magnets

Abstract

Semiconductor-ferromagnet GaAs-Fe3Si core-shell nanowires were grown by molecular beam epitaxy and analyzed by scanning and transmission electron microscopy, X-ray diffraction, Mössbauer spectroscopy, and magnetic force microscopy. We obtained closed and smooth Fe3Si shells with a crystalline structure that show ferromagnetic properties with magnetizations along the nanowire axis (perpendicular to the substrate). Such nanobar magnets are promising candidates to enable the fabrication of new forward-looking devices in the field of spintronics and magnetic recording.

Magnetic properties of GaAs-Fe3Si core-shell nanowires—A comparison of ensemble and single nanowire investigation

“…[1][2][3][4][5][6][7][8][9][10][11][12] To fabricate SFCSNws, commonly first semiconductor Nws are fabricated by epitaxial methods such as molecular beam epitaxy or metal oxide chemical vapor deposition and are in a second growth step coated with the ferromagnetic material. Thereby the magnetic material does not necessarily stick to the Nw shells exclusively.…”

“…Thus, the insight of ensemble measurements on the Nws themselves that were reported recently by using superconducting quantum interference device magnetometry (SQUID), small angle neutron scattering and ferromagnetic resonance techniques are quite equivocal. [1][2][3][4][5][6][7] Single Nw magnetic investigation on the other hand gives precise information about only the selected structure (one Nw shell) but thus it reflects only the information obtained from one single event of measurement (from one Nw). To draw conclusions from such measurements over all other Nws is hence quite limited.…”

“…To investigate single Nws, electrical measurements of the magnetoresistance, magnetic force microscopy (MFM) and nanoSQUID techniques were used so far in literature. 5 In this study, we give an overview and compare the capability of the commonly used magnetic ensemble and single Nw magnetic characterization on the basis of GaAs-Fe 3 Si core-shell Nws. Details on the growth and structural properties of these Nws can be found elsewhere.…”

Diffraction at GaAs/Fe3Si core/shell nanowires: The formation of nanofacets

“…[1][2][3][4][5][6][7][8] The cylindrical shape of the ferromagnet in such core/shell NWs causes a magnetization along the wire axis, i.e. perpendicular to the substrate surface.…”

“…[9][10][11][12][13] So we have choosen to grow GaAs/Fe 3 Si core/shell nanowire structures. 7 The nucleation of a film on a planar substrate as well as on a core NW surface can be considered in a similar manner as wetting or nonwetting of liquids. 14 If the film wets the substrate it will grow layer-by-layer in Frank van der Merwe growth mode.…”