TY  - JOUR
  - Kazakova, O.,Morgunov, R.,Kulkarni, J.,Holmes, J.,Ottaviano, L.
  - 2008
  - June
  - Physical Review B
  - Effect of magnetic defects and dimensionality on the spin dynamics of GeMn systems: Electron spin resonance measurements
  - Validated
  - ()
  - 77
  - 23
  - Effects of dimensionality on magnetic and electric properties of one- and two-dimensional GeMn systems and the role of defects in magnetic ordering are investigated by means of electron spin resonance (ESR) and superconducting quantum interference device magnetometry techniques. Arrays of Ge1-xMnx nanowires and thin Ge:Mn films with similar concentrations of the magnetic impurity (x=1%-8%) have been fabricated by chemical synthesis and ion implantation, respectively. In magnetically homogeneous Ge1-xMnx nanowires, all observed electron spin resonances are related to absorption on individual magnetic centers (Mn3+ and Mn2+ ions and polarized charge carriers) in a broad temperature range, T=5-300 K. On the other hand, in strongly inhomogeneous 2D GeMn films, a collective spin excitation, the spin-wave resonance, is observed at low temperatures, T=5-60 K. This signifies the presence of long-range spin states and a cooperative magnetic response originating from crystalline Mn5Ge3 precipitates and Mn-rich amorphous nanoclusters as well as diluted Mn ions. Additionally, a strong negative background was observed and attributed to the microwave magnetoresistance of the Ge:Mn thin films. The absence of the magnetoresistance in Ge1-xMnx nanowires indicates that the scattering of charge carriers is determined by dimensions of the structure. Overall, our analysis of magnetic-resonance phenomena reveals a significant difference between one-dimensional and two-dimensional magnetic semiconductors. It emphasizes the important role of dimensionality as well as the type and distribution of magnetic defects in spin-dependent scattering and dynamic magnetic properties of GeMn semiconductors.
  - 1098-0121
  - ://000257289500084
DA  - 2008/06
ER  - 

@article{V16860761,
   = {Kazakova,  O. and Morgunov,  R. and Kulkarni,  J. and Holmes,  J. and Ottaviano,  L. },
   = {2008},
   = {June},
   = {Physical Review B},
   = {Effect of magnetic defects and dimensionality on the spin dynamics of GeMn systems: Electron spin resonance measurements},
   = {Validated},
   = {()},
   = {77},
   = {23},
   = {{Effects of dimensionality on magnetic and electric properties of one- and two-dimensional GeMn systems and the role of defects in magnetic ordering are investigated by means of electron spin resonance (ESR) and superconducting quantum interference device magnetometry techniques. Arrays of Ge1-xMnx nanowires and thin Ge:Mn films with similar concentrations of the magnetic impurity (x=1%-8%) have been fabricated by chemical synthesis and ion implantation, respectively. In magnetically homogeneous Ge1-xMnx nanowires, all observed electron spin resonances are related to absorption on individual magnetic centers (Mn3+ and Mn2+ ions and polarized charge carriers) in a broad temperature range, T=5-300 K. On the other hand, in strongly inhomogeneous 2D GeMn films, a collective spin excitation, the spin-wave resonance, is observed at low temperatures, T=5-60 K. This signifies the presence of long-range spin states and a cooperative magnetic response originating from crystalline Mn5Ge3 precipitates and Mn-rich amorphous nanoclusters as well as diluted Mn ions. Additionally, a strong negative background was observed and attributed to the microwave magnetoresistance of the Ge:Mn thin films. The absence of the magnetoresistance in Ge1-xMnx nanowires indicates that the scattering of charge carriers is determined by dimensions of the structure. Overall, our analysis of magnetic-resonance phenomena reveals a significant difference between one-dimensional and two-dimensional magnetic semiconductors. It emphasizes the important role of dimensionality as well as the type and distribution of magnetic defects in spin-dependent scattering and dynamic magnetic properties of GeMn semiconductors.}},
  issn = {1098-0121},
   = {://000257289500084},
  source = {IRIS}
}