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Title: Compositional dependencies of ferromagnetic Ge{sub 1-x}Mn{sub x}Te grown by solid-source molecular-beam epitaxy

Abstract

The IV-VI diluted magnetic semiconductor Ge{sub 1-x}Mn{sub x}Te thin films on BaF{sub 2} (111) substrate have been prepared using solid-source molecular-beam epitaxy technique by varying the Mn concentrations from x=0.25 to 0.98. The chemical Mn concentration was determined by x-ray photoelectron spectroscopy measurement. The in situ reflection high-energy electron diffraction pattern indicates that the growth mechanism is in the island-growth mode. The x-ray diffraction shows that the Ge{sub 1-x}Mn{sub x}Te films crystallize in the NaCl phase with (111) orientation. A clear ferromagnetic ordering is observed in the detailed temperature-dependent magnetization measurement for 0.25<x<0.98. The dependence of Curie temperature T{sub C} on Mn concentration x tends to follow a quadratic behavior. This phenomenon can be attributed to the increase of antiferromagnetic interaction since MnTe is an antiferromagnet.

Authors:
; ; ;  [1]
  1. Information Storage Materials Laboratory, Electrical and Computer Engineering Department, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore) and Data Storage Institute, 5 Engineering Drive 1, Singapore 117608 (Singapore)
Publication Date:
OSTI Identifier:
20788116
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 99; Journal Issue: 8; Other Information: DOI: 10.1063/1.2170072; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANTIFERROMAGNETIC MATERIALS; ANTIFERROMAGNETISM; BARIUM FLUORIDES; CRYSTAL GROWTH; CURIE POINT; ELECTRON DIFFRACTION; FERROMAGNETIC MATERIALS; GERMANIUM COMPOUNDS; MAGNETIC SEMICONDUCTORS; MAGNETIZATION; MANGANESE TELLURIDES; MOLECULAR BEAM EPITAXY; SODIUM CHLORIDES; SUBSTRATES; TEMPERATURE DEPENDENCE; THIN FILMS; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Chen, W. Q., Teo, K. L., Jalil, M. B. A., and Liew, T. Compositional dependencies of ferromagnetic Ge{sub 1-x}Mn{sub x}Te grown by solid-source molecular-beam epitaxy. United States: N. p., 2006. Web. doi:10.1063/1.2170072.
Chen, W. Q., Teo, K. L., Jalil, M. B. A., & Liew, T. Compositional dependencies of ferromagnetic Ge{sub 1-x}Mn{sub x}Te grown by solid-source molecular-beam epitaxy. United States. doi:10.1063/1.2170072.
Chen, W. Q., Teo, K. L., Jalil, M. B. A., and Liew, T. Sat . "Compositional dependencies of ferromagnetic Ge{sub 1-x}Mn{sub x}Te grown by solid-source molecular-beam epitaxy". United States. doi:10.1063/1.2170072.
@article{osti_20788116,
title = {Compositional dependencies of ferromagnetic Ge{sub 1-x}Mn{sub x}Te grown by solid-source molecular-beam epitaxy},
author = {Chen, W. Q. and Teo, K. L. and Jalil, M. B. A. and Liew, T.},
abstractNote = {The IV-VI diluted magnetic semiconductor Ge{sub 1-x}Mn{sub x}Te thin films on BaF{sub 2} (111) substrate have been prepared using solid-source molecular-beam epitaxy technique by varying the Mn concentrations from x=0.25 to 0.98. The chemical Mn concentration was determined by x-ray photoelectron spectroscopy measurement. The in situ reflection high-energy electron diffraction pattern indicates that the growth mechanism is in the island-growth mode. The x-ray diffraction shows that the Ge{sub 1-x}Mn{sub x}Te films crystallize in the NaCl phase with (111) orientation. A clear ferromagnetic ordering is observed in the detailed temperature-dependent magnetization measurement for 0.25<x<0.98. The dependence of Curie temperature T{sub C} on Mn concentration x tends to follow a quadratic behavior. This phenomenon can be attributed to the increase of antiferromagnetic interaction since MnTe is an antiferromagnet.},
doi = {10.1063/1.2170072},
journal = {Journal of Applied Physics},
number = 8,
volume = 99,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • The optical, magnetic, and transport behaviors of Ge{sub 1-x}Mn{sub x}Te (x=0.24 and 0.55) grown by solid-source molecular-beam epitaxy are investigated. X-ray diffraction shows that Ge{sub 1-x}Mn{sub x}Te crystallizes in rocksalt structure. The temperature-dependent magnetization (M-T) for x=0.55 sample gives a Curie paramagnetic temperature of {theta}{sub p}{approx}180 K, which is consistent with the temperature-dependent resistivity {rho}(T) measurement. Anomalous Hall effect is clearly observed in the samples and can be attributed to extrinsic skew scattering based on the scaling relationship of {rho}{sub xy}{proportional_to}{rho}{sub xx}{sup 1.06}. The magnetoresistance of Ge{sub 1-x}Mn{sub x}Te is isotropic and displays a clear hysterestic loop at low temperature,more » which resembles that of giant-magnetoresistance granular system in solids.« less
  • Growth of the IV-VI diluted magnetic semiconductor Ge{sub 1-x}Mn{sub x}Te by molecular beam epitaxy is reported. The epitaxial growth of Ge{sub 1-x}Mn{sub x}Te (x=0.13) on BaF{sub 2} (111) with a GeTe buffer layer is confirmed by x-ray diffraction and reflection high-energy electron diffraction. The ferromagnetic order is clearly established by the magnetization and magnetotransport measurements. The Curie temperature of 100 K is obtained for the hole concentration of 7.86x10{sup 20} cm{sup -3}. The existence of the strong p-d exchange which gives rise to the ferromagnetic order is revealed by the hard x-ray photoemission measurements.
  • B-doped Si{sub 1{minus}{ital x}}Ge{sub {ital x}} layers with Ge fractions, determined by Rutherford backscattering spectroscopy, ranging from 0 to 0.28 and B concentrations, from quantitative secondary-ion spectroscopy measurements, between 5{times}10{sup 16} and 4{times}10{sup 19} cm{sup {minus}3} were grown on Si(001) at temperatures {ital T}{sub {ital s}}=475{endash}575{degree}C by gas-source molecular beam epitaxy from Si{sub 2}H{sub 6}, Ge{sub 2}H{sub 6}, and B{sub 2}H{sub 6}. Film thicknesses ranged from 200 nm for alloys with {ital x}=0.28 to 800 nm with {ital x}=0.05 to 1.4 {mu}m for Si. Structural analyses by high-resolution x-ray diffraction and reciprocal lattice mapping combined with transmission electron microscopy showedmore » that all films were fully strained, with measured relaxations of only {approx_equal}4{times}10{sup {minus}5}, and exhibited no evidence of dislocations or other extended defects. The hole conductivity mobility {mu}{sub {ital c},{ital h}} in these layers increased continuously with increasing Ge concentrations, whereas the Hall mobility decreased yielding a Hall scattering factor that ranged from 0.75 for Si to 0.26 for Si{sub 0.72}Ge{sub 0.28} but was not strongly affected by B concentration. {mu}{sub {ital c},{ital h}}, with {ital C}{sub B}=2{times}10{sup 18} cm{sup {minus}3}, varied from 110 cm{sup 2}V{sup {minus}1}s{sup {minus}1} for Si{sub 0.95}Ge{sub 0.05} to 158 cm{sup 2}V{sup {minus}1}s{sup {minus}1} for Si{sub 0.72}Ge{sub 0.28}, compared to 86 cm{sup 2}V{sup {minus}1}s{sup {minus}1} for Si, in good agreement with Boltzmann transport model calculations accounting for changes in the valence-band structure due to the effects of both alloying and biaxial in-plane compressional strain. {copyright} {ital 1996 American Institute of Physics.}« less
  • In this letter, we study the structural and magnetic properties of Ge{sub 1-x-y}Sn{sub x}Mn{sub y} films grown on Ge(001) by low temperature molecular beam epitaxy using X-ray diffraction, high resolution transmission electron microscopy, and superconducting quantum interference device. Like in Mn doped Ge films, Mn atoms diffuse during the growth and aggregate into vertically aligned Mn-rich nanocolumns of a few nanometers in diameter. Transmission electron microscopy observations in plane view clearly indicate that the Sn incorporation is not uniform with concentration in Mn rich vertical nanocolumns lower than the detection limit of electron energy loss spectroscopy. The matrix exhibits amore » GeSn solid solution while there is a Sn-rich GeSn shell around GeMn nanocolumns. The magnetization in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} layers is higher than in Ge{sub 1-x}Mn{sub x} films. This magnetic moment enhancement in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} is probably related to the modification of the electronic structure of Mn atoms in the nanocolumns by the Sn-rich shell, which is formed around the nanocolumns.« less
  • Group-IV ferromagnetic semiconductor Ge{sub 1-x}Fe{sub x} was grown by low-temperature molecular beam epitaxy without precipitation of ferromagnetic Ge-Fe intermetallic compounds. The ferromagnetism of Ge{sub 1-x}Fe{sub x} films was investigated by magnetic circular dichroism (MCD). In particular, the influence of the Fe content (x=2.0%-17.5%) and growth temperature (100 and 200 deg. C) on the ferromagnetism was carefully studied. The MCD measurements revealed that the overall spectral features reflecting the band structure of the Ge{sub 1-x}Fe{sub x} films were identical with those in bulk Ge, and that the large spin splitting of the band structure was induced by the incorporation of Femore » atoms into the Ge matrix, indicating the existence of s,p-d exchange interactions. The Ge{sub 1-x}Fe{sub x} films showed ferromagnetic behavior and the ferromagnetic transition temperature linearly increased with increasing the Fe concentration. These results indicate that the epitaxially grown Ge{sub 1-x}Fe{sub x} is an intrinsic ferromagnetic semiconductor.« less