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Intrinsic Half-Metallicity in Modified Graphene Nanoribbons (0902.1808v1)

Published 11 Feb 2009 in cond-mat.mtrl-sci and cond-mat.mes-hall

Abstract: We perform first-principles calculations based on density functional theory to study quasi one-dimensional edge-passivated (with hydrogen) zigzag graphene nanoribbons (ZGNRs) of various widths with chemical dopants, boron and nitrogen, keeping the whole system isoelectronic. Gradual increase in doping concentration takes the system finally to zigzag boron nitride nanoribbons (ZBNNRs). Our study reveals that, for all doping concentrations the systems stabilize in anti-ferromagnetic ground states. Doping concentrations and dopant positions regulate the electronic structure of the nanoribbons, exhibiting both semiconducting and half-metallic behaviors as a response to the external electric field. Interestingly, our results show that ZBNNRs with terminating polyacene unit exhibit half-metallicity irrespective of the ribbon width as well as applied electric field, opening a huge possibility in spintronics device applications.

Citations (344)

Summary

  • The paper demonstrates that strategic boron and nitrogen doping transforms zigzag graphene nanoribbons into intrinsic half-metallic systems crucial for spintronic applications.
  • It employs density functional theory to analyze how varying dopant concentrations and positions modulate the electronic structure and magnetic responses.
  • The findings highlight that controlled doping stabilizes an antiferromagnetic ground state and tunable band gaps, paving the way for practical device design.

Intrinsic Half-Metallicity in Modified Graphene Nanoribbons

The paper "Intrinsic Half-Metallicity in Modified Graphene Nanoribbons" by Sudipta Dutta, Arun K. Manna, and Swapan K. Pati presents a detailed theoretical paper into the electronic properties of zigzag graphene nanoribbons (ZGNRs) influenced by chemical modifications. The research utilizes density functional theory (DFT) to explore quasi-one-dimensional edge-passivated ZGNRs doped with boron and nitrogen, keeping the system isoelectronic, and investigates electronic and magnetic responses to an external electric field.

Key Findings

  1. Antiferromagnetic Ground State: For all doping concentrations examined, the studied systems exhibit stabilization in antiferromagnetic ground states. This configuration is integral to understanding the magnetic interactions in these nanostructures.
  2. Electronic Structure Modulation: The paper demonstrates that the varying concentrations and positions of dopants significantly influence the electronic structure of the nanoribbons. These modifications give rise to both semiconducting and half-metallic behaviors in response to imposed electric fields.
  3. Half-Metallicity in ZBNNRs: The results indicate a robust occurrence of half-metallicity in zigzag boron nitride nanoribbons (ZBNNRs) with terminating polyacene units, regardless of ribbon width and external electric field strength. Such a property is highly desirable for spintronic applications, which require materials that exhibit complete spin polarization.
  4. Electronic Band Gaps: The paper provides insight into how controlled doping concentrations can alter the band gaps of these nanoribbons. The observed deviations from expected symmetric spin distribution point to novel electronic properties in these engineered materials.

Implications

The implications of achieving intrinsic half-metallicity in modified graphene nanoribbons extend to the development of spintronic devices where enhanced control over spin channels is crucial. The substitution of carbon by boron-nitrogen pairs introduces notable electronic and magnetic changes, which have potential applications in next-generation electronic devices that leverage spin rather than charge for information processing.

The research highlights the potential of ZBNNRs in theoretical and applied physics, especially considering their observed half-metallicity under practical conditions such as room temperature, making experimental realization plausible.

Future Directions

Future research can expand on the findings of this paper by experimenting with other potential dopants and edge terminations to further explore and exploit the versatile electronic properties of graphene nanoribbons. The possibility of extending these findings to other two-dimensional materials should be investigated, as well as the scalability of such modified materials in real-world applications. Additionally, experimental verification of these theoretical predictions is essential to transition towards practical device fabrication.

In summary, this paper provides a comprehensive and insightful analysis of chemically modified graphene nanoribbons, emphasizing their potential for use in practical spintronic applications due to the intrinsic half-metallicity enabled by strategic chemical doping. The work opens avenues for further exploration of graphene-based materials in nanotechnology and materials science.

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