Mn-doped InAs self-organized diluted magnetic quantum-dot layers with Curie temperatures above 300 K

The magnetic and structural properties of InAs:Mn self-organized diluted magnetic quantum dots grown by low-temperature (∼270°C), solid-source molecular-beam epitaxy using a very low InAs growth rate (<0.1ML∕s) are investigated. A Curie temperature (TC) of ∼350K is measured in a sample grown with a Mn∕In flux ratio of 0.15. Electron energy-loss spectroscopy confirms that most of the Mn remains within the InAs quantum dots. We propose as a possible explanation for this high TC the effects of magnetic and structural disorder introduced by a random incorporation and inhomogeneous distribution of Mn atoms amongst the InAs quantum dots.

[1]  M. Berciu,et al.  Mean-field approach to ferromagnetism in (III,Mn)V diluted magnetic semiconductors at low carrier densities , 2001, cond-mat/0111045.

[2]  T. Dietl,et al.  Effect of thermodynamic fluctuations of magnetization on the bound magnetic polaron in dilute magnetic semiconductors , 1983 .

[3]  P. A. Wolff,et al.  Bound magnetic polaron interactions in insulating doped diluted magnetic semiconductors , 2002 .

[4]  M. Kakihana,et al.  Materials Research Society Symposium - Proceedings , 2000 .

[5]  Monte Carlo simulations of an impurity-band model for III-V diluted magnetic semiconductors , 2002, cond-mat/0203173.

[6]  H. Asahi,et al.  Magnetic and optical properties of Mn-including InAs dots grown by metalorganic molecular beam epitaxy , 2000 .

[7]  H. Ohno,et al.  Zener model description of ferromagnetism in zinc-blende magnetic semiconductors , 2000, Science.

[8]  S. Fathpour,et al.  Application of diluted magnetic semiconductors and quantum dots to spin polarized light sources , 2003 .

[9]  H. Ohno,et al.  Effect of low-temperature annealing on (Ga,Mn)As trilayer structures , 2003 .

[10]  H. Ohno,et al.  InAs and (In,Mn)As nanostructures grown on GaAs(100), (211)B, and (311)B substrates , 1999 .

[11]  H. Ohno,et al.  Surfactant effect of Mn on the formation of self-organized InAs nanostructures , 2000 .

[12]  H. Ohno,et al.  Fluorescence extended x-ray absorption fine structure study on local structures around Mn atoms in thin (In, Mn)As layer and (In, Mn)As quantum dots , 2001 .

[13]  D. D. Awschalom,et al.  Highly enhanced Curie temperature in low-temperature annealed [Ga,Mn]As epilayers , 2002 .

[14]  G. Medeiros-Ribeiro,et al.  Magnetic properties and imaging of Mn‐implanted GaAs semiconductors , 1996 .

[15]  A. M. Nazmul,et al.  Ferromagnetism and high Curie temperature in semiconductor heterostructures with Mn δ-doped GaAs and p-type selective doping , 2003 .