Effect of magnetic defects and dimensionality on the spin dynamics of GeMn systems: Electron spin resonance measurements

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O. Kazakova,¹ R. Morgunov,² J. Kulkarni,³ J. Holmes,³ and L. Ottaviano⁴
¹National Physical Laboratory, Teddington, TW11 0LW, United Kingdom
²Graduate School of Science, Hiroshima University, Higashi, Hiroshima 739-8526, Japan
³Department of Chemistry, University College Cork, Cork, Ireland
⁴CNISM-C.N.R. and Dipartimento di Fisica, Università dell'Aquila, Coppito, 67010 L'Aquila, Italy

Received 6 February 2008; revised 9 May 2008; published 20 June 2008

Effectsof dimensionality on magnetic and electric properties of one- andtwo-dimensional GeMn systems and the role of defects in magneticordering are investigated by means of electron spin resonance (ESR)and superconducting quantum interference device magnetometry techniques. Arrays of Ge_1−xMn_xnanowires and thin Ge:Mn films with similar concentrations of themagnetic impurity (x=1%–8%) have been fabricated by chemical synthesis andion implantation, respectively. In magnetically homogeneous Ge_1−xMn_x nanowires, all observedelectron spin resonances are related to absorption on individual magneticcenters (Mn³⁺ and Mn²⁺ ions and polarized charge carriers) ina broad temperature range, T=5–300 K. On the other hand, instrongly inhomogeneous 2D GeMn films, a collective spin excitation, thespin-wave resonance, is observed at low temperatures, T=5–60 K. This signifiesthe presence of long-range spin states and a cooperative magneticresponse originating from crystalline Mn₅Ge₃ precipitates and Mn-rich amorphous nanoclustersas well as diluted Mn ions. Additionally, a strong negativebackground was observed and attributed to the microwave magnetoresistance ofthe Ge:Mn thin films. The absence of the magnetoresistance inGe_1−xMn_x nanowires indicates that the scattering of charge carriers isdetermined by dimensions of the structure. Overall, our analysis ofmagnetic-resonance phenomena reveals a significant difference between one-dimensional and two-dimensionalmagnetic semiconductors. It emphasizes the important role of dimensionality aswell as the type and distribution of magnetic defects inspin-dependent scattering and dynamic magnetic properties of GeMn semiconductors.

URL:	http://link.aps.org/doi/10.1103/PhysRevB.77.235317
DOI:	10.1103/PhysRevB.77.235317
PACS:	75.50.Pp; 75.75.+a; 76.50.+g; 75.70.-i 75.50.Pp Magnetic semiconductors 75.75.+a Magnetic properties of nanostructures 76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance 75.70.-i Magnetic properties of thin films, surfaces, and interfaces YEAR: 2008
KEYWORDS:	elemental semiconductors, ferromagnetic resonance, germanium, germanium compounds, ion implantation, magnetic impurities, magnetic semiconductors, magnetic thin films, magnetoresistance, manganese, nanotechnology, nanowires, paramagnetic resonance, semiconductor doping, semiconductor thin films, spin dynamics

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C. Jaeger, C. Bihler, T. Vallaitis, S. T. B. Goennenwein, M. Opel, R. Gross, and M. S. Brandt, Phys. Rev. B 74, 045330 (2006).
C. Bihler, C. Jaeger, T. Vallaitis, M. Gjukic, M. S. Brandt, E. Pippel, J. Woltersdorf, and U. Gösele, Appl. Phys. Lett. 88, 112506 (2006).
M. Passacantando, L. Ottaviano, F. D'Orazio, F. Lucari, M. De Biase, G. Impellizzeri, and F. Priolo, Phys. Rev. B 73, 195207 (2006).
L. Ottaviano, M. Passacantando, S. Picozzi, A. Continenza, R. Gunnella, A. Verna, G. Bihlmayer, G. Impellizzeri, and F. Priolo, Appl. Phys. Lett. 88, 061907 (2006).
L. Ottaviano, M. Passacantando, A. Verna, R. Gunnella, E. Principi, A. Di Cicco, G. Impellizzeri, and F. Priolo, J. Appl. Phys. 100, 063528 (2006).
O. Kazakova, J. S. Kulkarni, J. D. Holmes, and S. O. Demokritov, Phys. Rev. B 72, 094415 (2005).
O. Kazakova, J. S. Kulkarni, D. C. Arnold, and J. D. Holmes, J. Appl. Phys. 101, 09H108 (2007).
T. Devillers, M. Jamet, A. Barski, V. Poydenot, P. Bayle-Guillemaud, E. Bellet-Amalric, S. Cherifi, and J. Cibert, Phys. Rev. B 76, 205306 (2007).
Y. Liou, P. W. Su, and Y. L. Shen, Appl. Phys. Lett. 90, 182508 (2007).
Y. Liou, M. S. Lee, and K. L. You, Appl. Phys. Lett. 91, 082505 (2007).
X. Huang, A. Makmal, J. R. Chelikowsky, and L. Kronik, Phys. Rev. Lett. 94, 236801 (2005).
E. Nielsen and R. N. Bhatt, Phys. Rev. B 76, 161202(R) (2007).
R. Arias and D. L. Mills, Phys. Rev. B 63, 134439 (2001).
S. Ahlers, D. Bougeard, N. Sircar, G. Abstreiter, A. Trampert, M. Opel, and R. Gross, Phys. Rev. B 74, 214411 (2006).
D. Bougeard, S. Ahlers, A. Trampert, N. Sircar, and G. Abstreiter, Phys. Rev. Lett. 97, 237202 (2006).
C. Zeng, S. C. Erwin, L. C. Feldman, A. P. Li, R. Jin, J. R. Thompson, and H. H. Weitering, Appl. Phys. Lett. 83, 5002 (2003).
B. Hoekstra, R. P. Stapele, and J. M. Robertson, J. Appl. Phys. 48, 382 (1977).
S. T. B. Goennenwein, T. Graf, T. Wassner, M. S. Brandt, M. Stutzmann, J. B. Philipp, R. Gross, M. Krieger, K. Zürn, P. Ziemann, A. Koeder, S. Frank, W. Schoch, and A. Waag, Appl. Phys. Lett. 82, 730 (2003).