FERROMAGNETIC SEMICONDUCTOR

Epitaxial lift-off of ferromagnetic (Ga,Mn)As nanoflakes for van der Waals heterostructures

Adv. Electron. Mater., 2019, doi: 10. 1002/aelm.201900345



The recent discovery of two-dimensional (2D) van der Waals (vdWs) ferromagnetic crystals provides an ideal platform for fundamental understanding of 2D magnetism, as well as the applications of low-power spintronic devices. The advances of vdWs heterostructures can couple the quasiparticle interaction between the 2D ferromagnetic material and others with engineered strain, chemistry, optical and electrical properties, providing an additional route to realize conceptual quantum phenomena and novel device functionalities, such as unprecedented control of the spin and valley pseudospin, extremely large tunneling magnetoresistance, etc. However, due to their instability, the handing of 2D ferromagnetic materials can only be carried out under the help of encapsulation with other 2D materials in a glove box, which is the biggest barrier towards the practical applications.



Now, Kai Yuan and colleagues from Peking University, and Chinese Academy of Sciences, introduce an approach about peeling-off and transfer of 2D ferromagnetic (Ga,Mn)As layers with thickness of ~10–20 nm grown by the molecular-beam epitaxy under ambient conditions. The lifted-off freestanding (Ga,Mn)As layer maintained its ferromagnetism. Using mechanically layer-by-layer vdWs heterostructure assembly technique, they successfully fabricated vdWs heterostructure devices based on the lifted-off (Ga,Mn)As, including hBN/(Ga,Mn)As top-gate Hall device and p-(Ga,Mn)As/n-MoS₂ heterojunction diode. The electrical transport measurements demonstrated the ferromagnetic nature and gate tunable magnetoresistance of the lifted-off (Ga,Mn)As layer. The ambient stable lifted-off ultrathin (Ga,Mn)As layer can be used as an alternative 2D ferromagnetic materials.



Gang Xiang (Sichuan University, Chengdu, China)



doi: 10.1088/1674-4926/40/8/080203