Structure and magnetism of Ge3Mn5 clusters

We have grown Ge3Mn5 clusters by codepositing germanium and manganese atoms on Ge(001) substrates using low temperature molecular beam epitaxy and further annealing the films at high temperature. Clusters are spherical and randomly distributed in the germanium film in epitaxial relationship with the diamond lattice. They exhibit a broad size distribution. By performing a careful x-ray diffraction analysis, we could find that 97% of Ge3Mn5 clusters have their c-axis perpendicular to the film plane while 3% exhibit in-plane c-axis. We could also show a slight in-plane distortion of the Ge3Mn5 lattice leading to a reduction of uniaxial magnetic anisotropy. These observations are well confirmed by complementary superconducting quantum interference device and electron paramagnetic resonance measurements.

[1]  T. Dietl,et al.  A story of high-temperature ferromagnetism in semiconductors. , 2010, Chemical Society reviews.

[2]  M. Helm,et al.  Memory effect of Mn$_5$Ge$_3$ nanomagnets embedded inside a Mn-diluted Ge matrix , 2009, 0910.4095.

[3]  V. Holý,et al.  Self-assembled Mn5Ge3 nanomagnets close to the surface and deep inside a Ge1-xMnx epilayer , 2009 .

[4]  Masaaki Tanaka,et al.  Electromotive force and huge magnetoresistance in magnetic tunnel junctions , 2009, Nature.

[5]  T. Metzger,et al.  Diffuse x-ray scattering from inclusions in ferromagnetic Ge1-xMnx layers , 2008 .

[6]  M. Farle,et al.  Electron spin resonance and microwave magnetoresistance in Ge:Mn thin films , 2008 .

[7]  J. Holmes,et al.  Effect of magnetic defects and dimensionality on the spin dynamics of GeMn systems: electron spin resonance measurements. , 2008 .

[8]  F. d’Acapito,et al.  Controlled aggregation of magnetic ions in a semiconductor: an experimental demonstration. , 2008, Physical review letters.

[9]  Y. Bando,et al.  Origin and control of high-temperature ferromagnetism in semiconductors. , 2007, Nature materials.

[10]  T. Devillers,et al.  Structure and magnetism of self-organized Ge(1-x)Mn(x) nano-columns , 2007, 0705.0566.

[11]  R. Gross,et al.  Magnetic and structural properties of GexMn1-x films: Precipitation of intermetallic nanomagnets , 2006, cond-mat/0611241.

[12]  A. Marty,et al.  High-Curie-temperature ferromagnetism in self-organized Ge1−xMnx nanocolumns , 2006, Nature materials.

[13]  T. Vallaitis,et al.  Structural and magnetic properties of Mn5Ge3 clusters in a dilute magnetic germanium matrix , 2006 .

[14]  S. Sugahara,et al.  Precipitation of Amorphous Ferromagnetic Semiconductor Phase in Epitaxially Grown Mn-Doped Ge Thin Films , 2005, cond-mat/0511361.

[15]  A. MacDonald,et al.  Ferromagnetic semiconductors: moving beyond (Ga,Mn)As , 2005, cond-mat/0503185.

[16]  T. Schulthess,et al.  Electronic structure and magnetic interactions in Mn doped semiconductors , 2001 .

[17]  D. Mailly,et al.  Magnetic anisotropy of a single cobalt nanocluster. , 2000, Physical review letters.

[18]  H. Ohno,et al.  Making nonmagnetic semiconductors ferromagnetic , 1998, Science.

[19]  J. B. Forsyth,et al.  The spatial distribution of magnetisation density in Mn5Ge3 , 1990 .

[20]  Kiyoo Sato,et al.  On the Magnetic Anisotropy of Single Crystal of Mn5Ge3 , 1963 .