We propose to develop new single crystal magnetic tunnel junctions (MTJs) based on the integration of crystalline and insulating NaCl ultra-thin films as an alternative to MgO tunnel barriers. Indeed, monocrystalline Fe/MgO/Fe MTJs are difficult to develop and stoichiometry at the interfaces is difficult to control. In this Ph.D. thesis, we will study the epitaxial growth of NaCl thin films on magnetic surfaces (iron, cobalt, Fe3O4...) and explore the magnetic properties and magneto-transport of magnetic tunnel junctions. Recent band structure calculations predict strong TMR effects in Fe/NaCl/Fe(001) MTJs up to several thousand percent.

The SPCSI has a long experience in the crystal growth of magnetic thin films under ultrahigh vacuum (metal, oxide) and related heterostructures by molecular beam epitaxy (MBE) and in the analysis of thin film morphology (scanning tunneling microscopy), measurements of physical properties (magnetism, transport) and modeling.

The objective of this thesis is therefore to develop single-crystal magnetic tunnel junctions with NaCl tunnel barriers whose performance exceeds that of MgO-based tunnel junctions. This work will consist to control the crystal growth of the different electrodes and barrier tunnel and then to study the magneto-transport properties of the devices. Electronic band structure calculations will be associated to the different transport and magneto-transport measurements.