MnAs dots grown on GaN( 000(1)over-bar)-(1x1) surface
Journal article, 2007

MnAs has been grown by means of MBE on the GaN(000 (1) over bar)-(1x1) surface. Two options of initiating the crystal growth were applied: (a) a regular MBE procedure (manganese and arsenic were delivered simultaneously) and (b) subsequent deposition of manganese and arsenic layers. It was shown that spontaneous formation of MnAs dots with the surface density of 1x10(11) cm(-2) and 2.5x10(11) cm(-2), respectively (as observed by atomic force microscopy), occurred for the layer thickness higher than 5 ML. Electronic structure of the MnAs/GaN systems was studied by resonant photoemission spectroscopy. That led to determination of the Mn 3d-related contribution to the total density of states distribution of MnAs. It has been proven that the electronic structures of the MnAs dots grown by the two procedures differ markedly. One corresponds to metallic, ferromagnetic NiAs-type MnAs, the other is similar to that reported for half-metallic zinc-blende MnAs. Both systems behave superparamagnetically (as revealed by magnetization measurements), but with both the blocking temperatures and the intradot Curie temperatures substantially different. The intradot Curie temperature is about 260 K for the former system while markedly higher than room temperature for the latter one. Relations between growth process, electronic structure, and other properties of the studied systems are discussed. Possible mechanisms of half-metallic MnAs formation on GaN are considered.

MANGANESE PNICTIDES

PHASE

FILMS

MAGNETIC-PROPERTIES

PHOTOEMISSION

BAND STRUCTURE

MOLECULAR-BEAM-EPITAXY

ELECTRONIC-STRUCTURE

FERROMAGNETIC MNAS

TRANSITION

Author

I. A. Kowalik

B. J. Kowalski

R. J. Iwanowski

K. Kopalko

E. Lusakowska

M. Sawicki

J. Sadowski

Martin Adell

Chalmers, Applied Physics, Solid State Physics

I. Grzegory

S. Porowski

Physical Review B - Condensed Matter and Materials Physics

24699950 (ISSN) 24699969 (eISSN)

Vol. 75 23 11-

Subject Categories

Other Engineering and Technologies

DOI

10.1103/PhysRevB.75.235303

More information

Created

10/7/2017