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A Group-IV Ferromagnetic Semiconductor: MnxGe1−x

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Science  25 Jan 2002:
Vol. 295, Issue 5555, pp. 651-654
DOI: 10.1126/science.1066348

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Abstract

We report on the epitaxial growth of a group-IV ferromagnetic semiconductor, MnxGe1−x, in which the Curie temperature is found to increase linearly with manganese (Mn) concentration from 25 to 116 kelvin. The p-type semiconducting character and hole-mediated exchange permit control of ferromagnetic order through application of a ±0.5-volt gate voltage, a value compatible with present microelectronic technology. Total-energy calculations within density-functional theory show that the magnetically ordered phase arises from a long-range ferromagnetic interaction that dominates a short-range antiferromagnetic interaction. Calculated spin interactions and percolation theory predict transition temperatures larger than measured, consistent with the observed suppression of magnetically active Mn atoms and hole concentration.

  • * Present address: School of Physics and CSCMR, Seoul National University, Seoul 151-747, Korea.

  • Present address: Micron Technology, Boise, ID 33707, USA.

  • Present address: Seagate Technology, Pittsburgh, PA 15203, USA.

  • § Present address: Boeing Satellite Systems, El Segundo, CA 90009, USA.

  • || To whom correspondence should be addressed. E-mail: jonker{at}nrl.navy.mil

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