Tailoring magnetic anisotropies
in ferromagnetic semiconductors
Konrad Dziatkowski
1st Erasmus Intensive Program Spintroni...
1st Erasmus Intensive Program Spintronics and Applications 2
Outline
1. Magnetic anisotropy – concept
2. Spintronics
3. Di...
1st Erasmus Intensive Program Spintronics and Applications 3
Outline
1. Magnetic anisotropy – concept
2. Spintronics
3. Di...
1st Erasmus Intensive Program Spintronics and Applications 4
Magnetic anisotropy
dependence of magnetic properties on the ...
1st Erasmus Intensive Program Spintronics and Applications 5
Magnetic anisotropy
http://roma2.rm.ingv.itsusceptibility
dep...
1st Erasmus Intensive Program Spintronics and Applications 6
Magnetic anisotropy
sample shape
shape (demagnetization) anis...
1st Erasmus Intensive Program Spintronics and Applications 7
Ferromagnetism
long-range ferromagnetic ordering
other types ...
1st Erasmus Intensive Program Spintronics and Applications 8
Inter-spin interactions
exchange interaction
dipol-dipol inte...
1st Erasmus Intensive Program Spintronics and Applications 9
Magnetic anisotropy and magnetic interactions
shape anisotrop...
1st Erasmus Intensive Program Spintronics and Applications 10
Magnetic anisotropy and magnetic interactions
exchange inter...
1st Erasmus Intensive Program Spintronics and Applications 11
Magnetic anisotropy and magnetic interactions
http://www.nat...
1st Erasmus Intensive Program Spintronics and Applications 12
Keyword summary – part I
dependence on orientation
shape ani...
1st Erasmus Intensive Program Spintronics and Applications 13
Outline
1. Magnetic anisotropy – concept
2. Spintronics
3. D...
1st Erasmus Intensive Program Spintronics and Applications 14
Spintronics (spin-based electronics)
a field of electronics ...
1st Erasmus Intensive Program Spintronics and Applications 15
Spintronics (spin-based electronics)
Magnetic RAM
Everspin
T...
1st Erasmus Intensive Program Spintronics and Applications 16
Spintronics (spin-based electronics)
knowing and understandi...
1st Erasmus Intensive Program Spintronics and Applications 17
Keyword summary – part II
further integration of devices
con...
1st Erasmus Intensive Program Spintronics and Applications 18
Outline
1. Magnetic anisotropy – concept
2. Spintronics
3. D...
1st Erasmus Intensive Program Spintronics and Applications 19
Dilute Magnetic Semiconductors
alloys of parent, nonmagnetic...
1st Erasmus Intensive Program Spintronics and Applications 20
Ferromagnetic DMSs
(Ga,Mn)As * (In,Mn)As * (Ga,Mn)N * (Zn,Mn...
1st Erasmus Intensive Program Spintronics and Applications 21
Ferromagnetic (Ga,Mn)As
low temperature molecular beam epita...
1st Erasmus Intensive Program Spintronics and Applications 22
Ferromagnetic (Ga,Mn)As
http://unix12.fzu.cz
reduction of:
>...
1st Erasmus Intensive Program Spintronics and Applications 23
Ferromagnetism of (Ga,Mn)As
exchange interaction between ban...
1st Erasmus Intensive Program Spintronics and Applications 24
Ferromagnetism of (Ga,Mn)As
exchange interaction between ban...
1st Erasmus Intensive Program Spintronics and Applications 25
Keyword summary – part III
non-magnetic host + magnetic dopa...
1st Erasmus Intensive Program Spintronics and Applications 26
Outline
1. Magnetic anisotropy – concept
2. Spintronics
3. D...
1st Erasmus Intensive Program Spintronics and Applications 27
Phenomenology of MA
Landau – Lifshitz – Gilbert equation
pre...
1st Erasmus Intensive Program Spintronics and Applications 28
Phenomenology of MA
M. Farle, Rep. Prog. Phys. 61, 755 (1998...
1st Erasmus Intensive Program Spintronics and Applications 29
Magnetization easy axis
energetically favorable direction of...
1st Erasmus Intensive Program Spintronics and Applications 30
Experimental methods
SQUID magnetometry
DC DC + mcrowaves
Fe...
1st Erasmus Intensive Program Spintronics and Applications 31
Experimental methods
http://photon-science.desy.de
SQUID mag...
1st Erasmus Intensive Program Spintronics and Applications 32
Experimental methods
DC + mcrowaves
Ferromagnetic resonance ...
1st Erasmus Intensive Program Spintronics and Applications 33
SQUID magnetometry
T. Hentschel et al., J. Phys. D: Appl. Ph...
1st Erasmus Intensive Program Spintronics and Applications 34
Ferromagnetic resonance
EA
HA
http://www.intechopen.com
easy...
1st Erasmus Intensive Program Spintronics and Applications 35
Keyword summary – part IV
free energy of magnetization
magne...
1st Erasmus Intensive Program Spintronics and Applications 36
Outline
1. Magnetic anisotropy – concept
2. Spintronics
3. D...
1st Erasmus Intensive Program Spintronics and Applications 37
Out-of-plane anisotropy
uniaxial shape anisotropy
shape for ...
1st Erasmus Intensive Program Spintronics and Applications 38
Out-of-plane anisotropy
in-plane EA perpendicular EA
X. Liu ...
1st Erasmus Intensive Program Spintronics and Applications 39
Out-of-plane anisotropy
X. Liu et al., Phys. Rev. B 67, 2052...
1st Erasmus Intensive Program Spintronics and Applications 40
Out-of-plane anisotropy
in-plane EA perpendicular EA
growth-...
1st Erasmus Intensive Program Spintronics and Applications 41
Out-of-plane anisotropy
M. Sawicki, J. Magn. Magn. Mater. 30...
1st Erasmus Intensive Program Spintronics and Applications 42
In-plane anisotropy
structure for fct
T. Wosinki et al., Phy...
1st Erasmus Intensive Program Spintronics and Applications 43
In-plane anisotropy
K. Dziatkowski et al., Phys. Rev. B 70, ...
1st Erasmus Intensive Program Spintronics and Applications 44
dependence on RF field
orientation
Atomic-steps-induced anis...
1st Erasmus Intensive Program Spintronics and Applications 45
partial strain relaxation
Strain-engineered anisotropy
F. Ho...
1st Erasmus Intensive Program Spintronics and Applications 46
Strain-engineered anisotropy
F. Hoffmann, Ph.D. Dissertation...
1st Erasmus Intensive Program Spintronics and Applications 47
Strain-engineered anisotropy
F. Hoffmann, Ph.D. Dissertation...
1st Erasmus Intensive Program Spintronics and Applications 48
Exchange bias
proximity effects
K. Dziatkowski et al., Appl....
1st Erasmus Intensive Program Spintronics and Applications 49
six-fold symmetry
Nanocomposites
(Ga,Mn)As with MnAs cluster...
1st Erasmus Intensive Program Spintronics and Applications 50
Keyword summary – part V
biaxial strain
unidirectional aniso...
1st Erasmus Intensive Program Spintronics and Applications 51
Thank you!
biaxial strain
unidirectional anisotropy
uniaxial...
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Tailoring Magnetic Anisotropies in Ferromagnetic Semiconductors

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Slightly shorter version of the presentation I gave for students of Erasmus summer school.

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Tailoring Magnetic Anisotropies in Ferromagnetic Semiconductors

  1. 1. Tailoring magnetic anisotropies in ferromagnetic semiconductors Konrad Dziatkowski 1st Erasmus Intensive Program Spintronics and Applications 1
  2. 2. 1st Erasmus Intensive Program Spintronics and Applications 2 Outline 1. Magnetic anisotropy – concept 2. Spintronics 3. Dilute Magnetic Semiconductors 4. Magnetic anisotropy – phenomenology and measurements 5. Examples of MA in DMSs Aim: understanding of experimental data on magnetic anisotropy
  3. 3. 1st Erasmus Intensive Program Spintronics and Applications 3 Outline 1. Magnetic anisotropy – concept 2. Spintronics 3. Dilute Magnetic Semiconductors 4. Magnetic anisotropy – phenomenology and measurements 5. Examples of MA in DMSs
  4. 4. 1st Erasmus Intensive Program Spintronics and Applications 4 Magnetic anisotropy dependence of magnetic properties on the orientation of external magnetic field http://photon-science.desy.de
  5. 5. 1st Erasmus Intensive Program Spintronics and Applications 5 Magnetic anisotropy http://roma2.rm.ingv.itsusceptibility dependence of magnetic properties on the orientation of external magnetic field
  6. 6. 1st Erasmus Intensive Program Spintronics and Applications 6 Magnetic anisotropy sample shape shape (demagnetization) anisotropy http://ocw.mit.edu http://www.physics.mcmaster.ca http://www.nanowerk.com http://www.nanowerk.com http://www.technologyreview.com crystal structure magnetocrystalline anisotropy dependence of magnetic properties on the orientation with respect to what?
  7. 7. 1st Erasmus Intensive Program Spintronics and Applications 7 Ferromagnetism long-range ferromagnetic ordering other types of order antiferromagnet ferrimagnet http://physics.tutorvista.com H = 0, M ≠ 0 dependence of magnetic properties on the orientation of what?
  8. 8. 1st Erasmus Intensive Program Spintronics and Applications 8 Inter-spin interactions exchange interaction dipol-dipol interaction
  9. 9. 1st Erasmus Intensive Program Spintronics and Applications 9 Magnetic anisotropy and magnetic interactions shape anisotropy dipol-dipol interaction: long range, directional
  10. 10. 1st Erasmus Intensive Program Spintronics and Applications 10 Magnetic anisotropy and magnetic interactions exchange interaction: short range, isotropic X
  11. 11. 1st Erasmus Intensive Program Spintronics and Applications 11 Magnetic anisotropy and magnetic interactions http://www.nature.com magnetocrystalline anisotropy spin-orbit interaction
  12. 12. 1st Erasmus Intensive Program Spintronics and Applications 12 Keyword summary – part I dependence on orientation shape anisotropy magnetocrystalline anisotropy spin-orbit interaction dipol-dipol interaction long range ferromagnetic ordering
  13. 13. 1st Erasmus Intensive Program Spintronics and Applications 13 Outline 1. Magnetic anisotropy – concept 2. Spintronics 3. Dilute Magnetic Semiconductors 4. Magnetic anisotropy – phenomenology and measurements 5. Examples of MA in DMSs
  14. 14. 1st Erasmus Intensive Program Spintronics and Applications 14 Spintronics (spin-based electronics) a field of electronics involving nanoscale devices in which the information is carried/stored with use of the spin of an electron rather than its electric charge magnitude of passed current is modulated by the relative orientation of the magnetization in ferromagnetic films P. A. Gruenberg, Rev. Mod. Phys. 80, 1531 (2008) A. Fert, Rev. Mod. Phys. 80, 1517 (2008)
  15. 15. 1st Erasmus Intensive Program Spintronics and Applications 15 Spintronics (spin-based electronics) Magnetic RAM Everspin Technologies Spin FET http://www.electroiq.com
  16. 16. 1st Erasmus Intensive Program Spintronics and Applications 16 Spintronics (spin-based electronics) knowing and understanding magnetic anisotropy is fundamental in designing and manufacturing of spintronic devices metal-based spintronics (magnetoelectronics) http://pnas.org integration of computational and storage functionalities all-semiconductor spintronics
  17. 17. 1st Erasmus Intensive Program Spintronics and Applications 17 Keyword summary – part II further integration of devices control of magnetization all-semiconductor spintronics
  18. 18. 1st Erasmus Intensive Program Spintronics and Applications 18 Outline 1. Magnetic anisotropy – concept 2. Spintronics 3. Dilute Magnetic Semiconductors 4. Magnetic anisotropy – phenomenology and measurements 5. Examples of MA in DMSs
  19. 19. 1st Erasmus Intensive Program Spintronics and Applications 19 Dilute Magnetic Semiconductors alloys of parent, nonmagnetic semiconductor (e.g. GaAs, CdTe) with the atoms of magnetic elements (e.g. Mn, Co) host materials: III-V: GaAs, GaP, GaN, AlAs, AlN, InAs, InN, InP, ... II-VI: CdTe, CdSe, CdS, ZnTe, ZnS, PbTe, ... IV: Ge, Si magnetic dopants: Mn, Cr, Fe, Co, ... http://www.ohno.riec.tohoku.ac.jp
  20. 20. 1st Erasmus Intensive Program Spintronics and Applications 20 Ferromagnetic DMSs (Ga,Mn)As * (In,Mn)As * (Ga,Mn)N * (Zn,Mn)O * (Zn,Co)O * ... (Ga,Mn)As exhibits the highest Curie temperature: 170 ~ 190 K L. Chen et al., Appl. Phys. Lett. 95, 182505 (2009) H. Ohno, J. Appl. Phys. 113, 136509 (2013) HL. Wang et al., Sci China-Phys Mech Astron 56, 99 (2013) A. Bonanni and T. Dietl, Chem. Soc. Rev. 39, 528 (2010) K. Y. Wang et al., AIP Conf. Proc. 772, 333 (2005)
  21. 21. 1st Erasmus Intensive Program Spintronics and Applications 21 Ferromagnetic (Ga,Mn)As low temperature molecular beam epitaxy + post growth annealing after: H. Ohno, J. Magn. Magn. Mater. 200, 110 (1999) http://unix12.fzu.cz
  22. 22. 1st Erasmus Intensive Program Spintronics and Applications 22 Ferromagnetic (Ga,Mn)As http://unix12.fzu.cz reduction of: >> magnetization >> concentration of holes >> Curie temperature • substitutional manganese MnGa >> electronic configuration: 3d5 >> acceptor >> Bohr magnetons per ion: 5 • interstitial manganese >> double donor (electric compensation) >> antiferromagnetic coupling with substitutional manganese (magnetic compensation) • antistructural defect AsGa >> native for LT-MBE
  23. 23. 1st Erasmus Intensive Program Spintronics and Applications 23 Ferromagnetism of (Ga,Mn)As exchange interaction between band holes and manganese ions band holes of p shell localized electrons from d shell of Mn ions Jpd < 0 T. Jungwirth et al., Rev. Mod. Phys. 78, 809 (2006) S. Ohya et al., Nature Physics 7, 342, (2011)
  24. 24. 1st Erasmus Intensive Program Spintronics and Applications 24 Ferromagnetism of (Ga,Mn)As exchange interaction between band holes and manganese ions band holes of p shell localized electrons from d shell of Mn ions Jpd < 0 T. Jungwirth et al., Rev. Mod. Phys. 78, 809 (2006) effective RKKY-like interaction between manganese ions F. Matsukura et al., Phys. Rev. B 57, R2037 (1998) ferromagnetic Mn-Mn coupling
  25. 25. 1st Erasmus Intensive Program Spintronics and Applications 25 Keyword summary – part III non-magnetic host + magnetic dopants substitutional Mn interstitial Mn LT-MBE + annealing acceptor double donor hole-mediated ferromagnetism
  26. 26. 1st Erasmus Intensive Program Spintronics and Applications 26 Outline 1. Magnetic anisotropy – concept 2. Spintronics 3. Dilute Magnetic Semiconductors 4. Magnetic anisotropy – phenomenology and measurements 5. Examples of MA in DMSs
  27. 27. 1st Erasmus Intensive Program Spintronics and Applications 27 Phenomenology of MA Landau – Lifshitz – Gilbert equation precession damping L. Berger, Phys. Rev. B 54, 9353 (1996) J.C. Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996) other torques
  28. 28. 1st Erasmus Intensive Program Spintronics and Applications 28 Phenomenology of MA M. Farle, Rep. Prog. Phys. 61, 755 (1998) shape Zeeman structure for uniform field for thin layer for fct magnetization free energy
  29. 29. 1st Erasmus Intensive Program Spintronics and Applications 29 Magnetization easy axis energetically favorable direction of spontaneous magnetization minimum of magnetization free energy
  30. 30. 1st Erasmus Intensive Program Spintronics and Applications 30 Experimental methods SQUID magnetometry DC DC + mcrowaves Ferromagnetic resonance (FMR) other techniques: vibrating sample magnetometry, magnetotransport, polarized neutron reflectometry, magneto-optical Kerr effect, ...
  31. 31. 1st Erasmus Intensive Program Spintronics and Applications 31 Experimental methods http://photon-science.desy.de SQUID magnetometry DC
  32. 32. 1st Erasmus Intensive Program Spintronics and Applications 32 Experimental methods DC + mcrowaves Ferromagnetic resonance (FMR)
  33. 33. 1st Erasmus Intensive Program Spintronics and Applications 33 SQUID magnetometry T. Hentschel et al., J. Phys. D: Appl. Phys. 45, 055002 (2012) EAHA V. Z. C. Paes et al., J. Phys.: Condens. Matter 25, 046003 (2013) easy axis = lowest field needed for saturation
  34. 34. 1st Erasmus Intensive Program Spintronics and Applications 34 Ferromagnetic resonance EA HA http://www.intechopen.com easy axis = minimum of resonance field
  35. 35. 1st Erasmus Intensive Program Spintronics and Applications 35 Keyword summary – part IV free energy of magnetization magnetometry magnetization easy axis ferromagnetic resonance LLG equation minimum of resonance field
  36. 36. 1st Erasmus Intensive Program Spintronics and Applications 36 Outline 1. Magnetic anisotropy – concept 2. Spintronics 3. Dilute Magnetic Semiconductors 4. Magnetic anisotropy – phenomenology and measurements 5. Examples of MA in DMSs
  37. 37. 1st Erasmus Intensive Program Spintronics and Applications 37 Out-of-plane anisotropy uniaxial shape anisotropy shape for thin layer in-plane EA or easy plane K. Dziatkowski et al., Phys. Rev. B 70, 115202 (2004)
  38. 38. 1st Erasmus Intensive Program Spintronics and Applications 38 Out-of-plane anisotropy in-plane EA perpendicular EA X. Liu et al., Phys. Rev. B 67, 205204 (2003)
  39. 39. 1st Erasmus Intensive Program Spintronics and Applications 39 Out-of-plane anisotropy X. Liu et al., Phys. Rev. B 67, 205204 (2003)
  40. 40. 1st Erasmus Intensive Program Spintronics and Applications 40 Out-of-plane anisotropy in-plane EA perpendicular EA growth-related uniaxial magnetocrystalline anisotropy shape structure for thin layer for fct http://www.ohno.riec.tohoku.ac.jp
  41. 41. 1st Erasmus Intensive Program Spintronics and Applications 41 Out-of-plane anisotropy M. Sawicki, J. Magn. Magn. Mater. 300, 1 (2006) (perpendicular) Spin Reorientation Transition samples with low holes concentration
  42. 42. 1st Erasmus Intensive Program Spintronics and Applications 42 In-plane anisotropy structure for fct T. Wosinki et al., Physica E 51, 128 (2013)K. Dziatkowski et al., Phys. Rev. B 70, 115202 (2004) biaxial + (in-plane) uniaxial M. Birowska et al., Phys. Rev. Lett. 108, 237203 (2012) anisotropy of Mn-Mn pair energy
  43. 43. 1st Erasmus Intensive Program Spintronics and Applications 43 In-plane anisotropy K. Dziatkowski et al., Phys. Rev. B 70, 115202 (2004) (in plane) Spin Reorientation Transition
  44. 44. 1st Erasmus Intensive Program Spintronics and Applications 44 dependence on RF field orientation Atomic-steps-induced anisotropy K. Dziatkowski et al., J. Appl. Phys. 109, 07C301 (2011)
  45. 45. 1st Erasmus Intensive Program Spintronics and Applications 45 partial strain relaxation Strain-engineered anisotropy F. Hoffmann, Ph.D. Dissertation, U. of. Regensburg
  46. 46. 1st Erasmus Intensive Program Spintronics and Applications 46 Strain-engineered anisotropy F. Hoffmann, Ph.D. Dissertation, U. of. Regensburg partial strain relaxation, shape anisotropy
  47. 47. 1st Erasmus Intensive Program Spintronics and Applications 47 Strain-engineered anisotropy F. Hoffmann, Ph.D. Dissertation, U. of. Regensburg shape anisotropy
  48. 48. 1st Erasmus Intensive Program Spintronics and Applications 48 Exchange bias proximity effects K. Dziatkowski et al., Appl. Phys. Lett. 88, 142513 (2006) K. Dziatkowski et al., Acta Phys. Polon. A 110, 319 (2006) unidirectional anisotropy
  49. 49. 1st Erasmus Intensive Program Spintronics and Applications 49 six-fold symmetry Nanocomposites (Ga,Mn)As with MnAs clusters T. Hartmann et al., Physica E 13, 572 (2002)
  50. 50. 1st Erasmus Intensive Program Spintronics and Applications 50 Keyword summary – part V biaxial strain unidirectional anisotropy uniaxial out-of-plane anisotropy uniaxial in-plane anisotropy spin reorientation transition
  51. 51. 1st Erasmus Intensive Program Spintronics and Applications 51 Thank you! biaxial strain unidirectional anisotropy uniaxial out-of-plane anisotropy uniaxial in-plane anisotropy spin reorientation transition dependence on orientation shape anisotropy magnetocrystalline anisotropy spin-orbit interaction dipol-dipol interaction long range ferromagnetic ordering further integration of devices control of magnetization all-semiconductor spintronics non-magnetic host + magnetic dopants substitutional Mn interstitial Mn LT-MBE + annealing acceptor double donor hole-mediated ferromagnetism free energy of magnetization magnetometry magnetization easy axis ferromagnetic resonance LLG equation minimum of resonance field

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