Growth and study of nanostructured ferromagnetic semiconductors for spintronics

The emerging field of spintronics would be dramatically boosted if room-temperature ferromagnetism could be added to semiconductor nanostructures that are compatible with silicon technology.

In spintronics applications, magnetic properties (remanent states and spin-polarized carriers) may be conveyed by conventional metallic ferromagnets or by so-called ferromagnetic semiconductors. In addition, because in these semiconductors ferromagnetism is driven by carriers, magnetic properties may be controlled by an electrical field through the application of a gate voltage. Among many possible applications, carrier-controlled ferromagnetism, spin injection into nanostructures, and spin collection, could permit giant magnetoresistance-type memories, field sensors, spin transistors and reconfigurable logics, or even quantum information processing.

Until now, semiconductor spintronics has mainly been devised based on diluted magnetic semiconductors, in which magnetic atoms randomly substitute the semiconductor atoms. The presence of secondary phases or inhomogeneities (e.g. metallic inclusions, semiconducting ferromagnetic phase or simply concentration modulation) could increase the critical temperature, or enhance the magnetoresistance by multiplying the number of interfaces for spin scattering. Selforganization of the secondary phase could lead to arrays of interacting magnetic memory dots, or act as nanochannels for spin injection and collection in semiconductors. 

 

Within this context we grow and study GeMn material. 

 
(a) The TEM images of (Ge,Mn) _lms grown on GOI substrate. Mn-rich nanocolumns are shown for Mn concentration of (b) 6% and (c) 10%.

Transition from 2D to 3D growth mode. HAADF-HRSTEM images of (a) 3 ML, (b) 4 ML and (c) 6 ML Ge grown at a temperature of 450 °C. (d) General view of the 6ML Ge shown in (c).

 

 

More information on our work is in:

 

Or contact the principal investigator: André Barski.

 

Maj : 27/09/2016 (827)

 

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