1. Tunable half-metalicity in substitutionally doped boronitrene
A M Ukpong and N Chetty
Department of Physics
University of Pretoria

2. Spintronic effects in graphenic systems
Spintronics: based on ability to manipulate electronic charge and spin
Spontaneous magnetism in carbon-only materials (s and p electrons)
Half-metallicity (HM) in open-volume defective boronitrene due to electron injection
HM by doping with self-assembled clusters of B, C and N. Is this tunable?
Graphene
Boronitrene
A. M. Ukpong, N Chetty, J. Phys. Condens. Matter 24, (2012)

3. Substitutional complexes
T. B. Ngwenya, A. M. Ukpong, and N. Chetty, Phys. Rev. B 84, (2011)

4. Computational details
Spin-polarised/nonmagnetic calculations: VASP
Electron-ion interactions: (PAW)
XC potential: GGA-PBE
KEcutoff = 500 eV ; SCFconvergence <= 10-7 eV
Structure relaxations: Fatom <= eV/Å
Total energy converged wrt k-points:
12×12×1 (h-BN unit cell)
 = ET (50 atoms) - ET (128 atoms)  meV
C6B+C10N complex

5. Local structure reconstruction

6. Local structure reconstruction
(d)
Local structure reconstruction

7. Energetics
-2.6   (eV)  2.6
S B Zhang and J E Northrup, Phys. Rev. Lett. 67, 2339 (1991)

8. Effects of edge termination
Energetic stability
Effects of edge termination
E (STP) = E[C1B+C3N ] – E[C1N+C3B ]
= eVmol-1

9. Spin polarised electronic charge density

10. Spin polarised electronic charge density

11. P = [N(EF) - N(EF)]/(N(EF) + N(EF))
Magnetoelectronic signatures
P = [N(EF) - N(EF)]/(N(EF) + N(EF))
Δ = N(EF) - N(EF) > 0
Half-metallicity

13. Origin of half-metallicity
s-orbital DOS
p-orbital DOS

14. Magnetic polarization density

15. Magnetic exchange and magnetization
energy Em in hybrid BCN monolayers.
Complexes NC
Spin order
Em (eV)
J (eV)
m (µB)
B3N HM
0.21
0.42
1.99
N3B
HMFM
0.00
C1B+C3N (or C1N+C3B) 4
0.33
0.66
2.00 (1.99)
C3B+C3N 6
AFM
C3B +C6N (or C6B+C3N) 9
0.72
1.42
3.14(3.04)
C6B+C10N (or C6N+C10B) 16
0.90
1.80
3.77(3.33)

16. Tuning the magnetic moments
Stoichiometric
Non-stoichiometric

17. Tuning the half-metallicity Effect of charge injection
C1B+C3N complex

18. Half-metallicity is induced in boronitrene by doping:
Summary/Outlook
Half-metallicity is induced in boronitrene by doping:
(i) Self-assembled clusters of boron or carbon.
(ii) Engineering the geometry of the C-clusters (graphene flake)
(iii) Hexagonal flake (not half-metallic); triangular (half-metallic)
Tunable to HM ferrimagnetism by charge injection
(i) Applications in spintronics: SPLED, caloritronics, spin filters, and many more !!!
Possible tuning to HM ferrimagnetism by heat*
(i) Zero magnetization (Curie point ≥ 1250 K)
(ii) Violation of Curie–Weiss law in B3N complex
* A. M. Ukpong, and N. Chetty, Phys. Rev. B (July 2012) UNDER REVIEW

19. University of Pretoria
Acknowledgments
Naitore Gituma
Helpful discussions
Prof. Jannie Pretorius
UP Computational Cluster Support
University of Pretoria
Grant No: E2020 (Project No. 5)