Structural, Magnetic and Electronic Properties of Dilute MnScN(001) Grown by RF Nitrogen Plasma Molecular Beam Epitaxy
- PDF / 432,321 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 89 Downloads / 157 Views
Structural, Magnetic and Electronic Properties of Dilute MnScN(001) Grown by RF Nitrogen Plasma Molecular Beam Epitaxy
Costel Constantin,1 Kangkang Wang,2 Abhijit Chinchore,2 Han-Jong Chia3, John Markert3, Arthur R. Smith,2 1
Department of Physics and Astronomy, James Madison University Harrisonburg, VA 22801 Nanoscale & Quantum Phenomena Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 3 Department of Physics, University of Texas at Austin, Austin, TX 78712 2
ABSTRACT
The structural, magnetic, and electronic properties of dilute Mn-doped scandium nitride thin films grown by radio frequency N-plasma molecular beam epitaxy are explored. The results indicate a small magnetization extending up to as high as 350K. There is a slight dependence on the manganese concentration, with the lower Mn concentration showing a larger saturation magnetization. INTRODUCTION
In recent years there has been much interest in obtaining III-V dilute magnetic semiconductors (DMS’s) by doping semiconductors, such as gallium nitride (GaN) and gallium arsenide (GaAs), with transition metals (TM) such as manganese (Mn). For MnGaAs, the reported values for TC were previously limited to 110K [1], and this limit remained in place for many years. More recently, post-growth annealing treatments have made it possible to surpass this barrier, however, even with this method, TC in MnGaAs remains around 173K [2]. After the exciting prediction of Dietl et al. [3] in 2000 who stated that 5% Mn concentration in GaN or ZnO can raise the TC above room temperature, many experimental studies reported growth and magnetic properties of MnGaN [4-8]. Interestingly, these studies show that ferromagnetism including the Curie point (TC) strongly depends on the growth mode. Haider et al. [7] showed that N-rich and slight metal-rich growth regimes of MnGaN result in TC above 300K. Recently, Alexandrov et al. [9] reported electric field-dependent magnetic properties for MnGaN, showing a 39% decrease in saturation magnetization (MSAT) with applied voltage over the range 0-5 V. Despite some successes, it is important to realize that limitations in the rapid development of DMS materials can be related to dopant incorporation issues, and this was realized from the very beginning of DMS research. For the GaAs system, there are two types of point defects that are believed to preclude achieving very high TC values - Mn intersitials and As antisites, both of which act as double donors. There are suspicions that difficulty for the Mn to occupy the cation sites in GaAs (and in GaN) is attributed to mismatch in bonding (octhahedral vs. tetrahedral). Mn tends towards octahedral bonding in manganese nitride - MnxNy alloys mostly have rocksalttype tetragonal structure [10] (with the exception of the ζ-phase which reportedly has hexagonal structure [11,12]), whereas cations in GaAs and GaN have tetrahedral bonding.
It is therefore of great interest to investigate DMS systems in which there is the possibility of isostructural bonding between the
Data Loading...
