2013/01/28 by Samer Kahwaji, S. Kahwaji, R. A. Gordon +7 · 13 citations
Chemistry · Materials Science · Physics and Astronomy · #Analytical Chemistry (journal) #Chemistry #Condensed matter physics #Crystallography #Curie temperature #Ferromagnetism #Magnetic Properties and Applications #Magnetic field #Magnetic properties of thin films #Magnetic semiconductor #Magnetization #Materials science #Physics #ZnO doping and properties #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.88.174419
published in Physical Review B 88(17) (American Physical Society) · 10 pages, 8 figures
arxiv created 2013/01/28 · openalex publication_date 2013/11/22 · arxiv updated 2015/06/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present an investigation of Mn \ensuremathδ-doped layers in Si(001) grown by molecular beam epitaxy. We discovered that a Pb surfactant has significant effect on the structural and magnetic properties of the submonolayer of Mn, which depends on the Si capping layer growth temperature TSi, and the Mn coverage \ensuremathθMn. The results presented in this paper identify three regions in the growth-phase diagram characterized by distinct magnetic behaviors and crystal structures. In one region, x-ray absorption fine structure and transmission electron microscopy experiments indicate that MnSi nanocrystallites form with B2-like crystal type structures. At the optimal growth conditions, TSi = 200\phantom\rule0.16em0ex^\ensuremath∘C and \ensuremathθMn=0.26 monolayer, a ferromagnetic phase develops with a Curie temperature TC>400 K and a saturation moment msat=1.56 \ensuremathμB/Mn, whereas TC drops to zero for a control sample prepared without Pb. For TSi>200\phantom\rule0.16em0ex^\ensuremath∘C MnSi-B20 type precipitates form with a TC\ensuremath≈170 K. Rutherford backscattering spectrometry shows that the increase in the remanent magnetization in these two phases is possibly correlated with an increase in the Mn substitutional fraction, which suggests that a Si_1\ensuremath-xMnx dilute magnetic semiconductor may be forming in the matrix between the precipitates. Density functional calculations show that Pb changes the pathway by which the Mn atoms access the Si substitutional sites, MnSi. While the Pb increases the formation energy of MnSi at the Si surface, it enables substitutional incorporation by lowering the formation energy of Si vacancies by 0.92 eV.