Correlation between morphology, chemical environment, and ferromagnetism in the intrinsic-vacancy dilute magnetic semiconductor Cr-doped Ga2Se3/Si(001)

Journal Article · Fri Jan 28 04:00:00 EST 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.83.045203· OSTI ID:1019468

Yitamben, E N; Arena, D; Lovejoy, T C; Pakhomov, A B; Heald, S M; Negusse, E; Ohuchi, F S; Olmstead, M A

Chromium-doped gallium sesquiselenide, Cr:Ga{sub 2}Se{sub 3}, is a member of a new class of dilute magnetic semiconductors exploiting intrinsic vacancies in the host material. The correlation among room-temperature ferromagnetism, surface morphology, electronic structure, chromium concentration, and local chemical and structural environments in Cr:Ga{sub 2}Se{sub 3} films grown epitaxially on silicon is investigated with magnetometry, scanning tunneling microscopy, photoemission spectroscopy, and x-ray absorption spectroscopy. Inclusion of a few percent chromium in Ga{sub 2}Se{sub 3} results in laminar, semiconducting films that are ferromagnetic at room temperature with a magnetic moment 4{micro}{sub B}/Cr. The intrinsic-vacancy structure of defected-zinc-blende {beta}-Ga{sub 2}Se{sub 3} enables Cr incorporation in a locally octahedral site without disrupting long-range order, determined by x-ray absorption spectroscopy, as well as strong overlap between Cr 3d states and the Se 4p states lining the intrinsic-vacancy rows, observed with photoemission. The highest magnetic moment per Cr is observed near the solubility limit of roughly one Cr per three vacancies. At higher Cr concentrations, islanded, metallic films result, with a magnetic moment that depends strongly on surface morphology. The effective valence is Cr{sup 3+} in laminar films, with introduction of Cr{sup 0} upon islanding. A mechanism is proposed for laminar films whereby ordered intrinsic vacancies mediate ferromagnetism.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: DOE - OFFICE OF SCIENCE
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1019468
• Report Number(s): BNL--94927-2011-JA; KC0401030
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 4 Vol. 83; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTROSCOPY
CHROMIUM
ELECTRONIC STRUCTURE
FERROMAGNETISM
GALLIUM
LINERS
MAGNETIC MOMENTS
MAGNETIC SEMICONDUCTORS
MORPHOLOGY
PHOTOEMISSION
SCANNING TUNNELING MICROSCOPY
SILICON
SOLUBILITY
SPECTROSCOPY
VACANCIES
VALENCE
national synchrotron light source