All-Wurtzite (In,Ga)As-(Ga,Mn)As Core Shell Nanowires Grown by Molecular Beam Epitaxy

作者：Siusys Aloyzas^*; Sadowski Janusz; Sawicki Maciej; Kret Slawomir; Wojciechowski Tomasz; Gas Katarzyna; Szuszkiewicz Wojciech; Kaminska Agnieszka; Story Tomasz

来源：Nano Letters, 2014, 14(8): 4263-4272.

DOI：10.1021/nl500896d

• Magnetic semiconductor nanowires
• core-shell structures
• spintronics
• wurtzite (Ga,Mn)As
• superparamagnetism
• molecular beam epitaxy

Structural and magnetic properties of (In,Ga)As-(Ga,Mn)As core shell nanowires grown by molecular beam epitaxy on GaAs(111)B substrate with gold catalyst have been investigated. (In,Ga)As core nanowires were grown at high temperature (500 degrees C) whereas (Ga,Mn)As shells were deposited on the {1 (1) over bar 00} side facets of the cores at much lower temperature (220 degrees C). High-resolution transmission electron microscopy images and high spectral resolution Raman scattering data show that both the cores and the shells of the nanowires have wurtzite crystalline structure. Scanning and transmission electron microscopy observations show smooth (Ga,Mn)As shells containing 596 of Mn epitaxially deposited on (In,Ga)As cores containing about 10% of In without any misfit dislocations at the core shell interface. With the In content in the (In,Ga)As cores larger than 5% the (In,Ga)As lattice parameter is higher than that of (Ga,Mn)As and the shell is in the tensile strain state. Elaborated magnetic studies indicate the presence of ferromagnetic coupling in (Ga,Mn)As shells at the temperatures in excess of 33 K This coupling is maintained only in separated mesoscopic volumes resulting in an overall superparamagnetic behavior which gets blocked below similar to 17 K

• 出版日期2014-8