Room Temperature Ferromagnetic Mn:Ge(001)
| Autor: | Florin Vasiliu, C. M. Teodorescu, Ioana Cristina Bucur, Nicoleta Răduţoiu, Laura E. Stoflea, Liviu Cristian Tanase, Ionel Mercioniu, Victor Kuncser, G. A. Lungu |
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| Rok vydání: | 2013 |
| Předmět: |
Materials science
Analytical chemistry superconducting quantum interference device (SQUID) magnetometry lcsh:Technology Article Mn-Ge ferromagnetism law.invention magneto optical Kerr effect (MOKE) X-ray photoelectron spectroscopy low energy electron diffraction (LEED) law Phase (matter) General Materials Science lcsh:Microscopy High-resolution transmission electron microscopy lcsh:QC120-168.85 lcsh:QH201-278.5 Low-energy electron diffraction lcsh:T scanning tunneling microscopy (STM) X-ray photoelectron spectroscopy (XPS) Magnetic semiconductor diluted magnetic semiconductors (DMS) molecular beam epitaxy (MBE) high resolution transmission electron microscopy (HRTEM) Ferromagnetism lcsh:TA1-2040 lcsh:Descriptive and experimental mechanics lcsh:Electrical engineering. Electronics. Nuclear engineering Scanning tunneling microscope lcsh:Engineering (General). Civil engineering (General) lcsh:TK1-9971 Superparamagnetism |
| Zdroj: | Materials Volume 7 Issue 1 Pages 106-129 Materials, Vol 7, Iss 1, Pp 106-129 (2013) |
| ISSN: | 1996-1944 |
| DOI: | 10.3390/ma7010106 |
| Popis: | We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001), heated at relatively high temperature (starting with 250 °C). The samples were characterized by low energy electron diffraction (LEED), scanning tunneling microscopy (STM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), superconducting quantum interference device (SQUID), and magneto-optical Kerr effect (MOKE). Samples deposited at relatively elevated temperature (350 °C) exhibited the formation of ~5–8 nm diameter Mn5Ge3 and Mn11Ge8 agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe~2.5 phase, or manganese diluted into the Ge(001) crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm) deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge–Ge dimers on Ge(001). The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed. |
| Databáze: | OpenAIRE |
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