Overview
Research introduces Dirac cones into two-dimensional (2D) d-wave altermagnets as a strategy to develop spin sources characterized by both high charge-to-spin conversion efficiency (CSE) and high charge conductivity. This approach addresses challenges in achieving these dual properties within existing altermagnetic materials for applications such as magnetic random-access memories (MRAMs).
Research Context
Magnetic random-access memories require spin sources that demonstrate both low critical charge-current density and low energy dissipation. Fulfilling these requirements necessitates spin sources with high charge-to-spin conversion efficiency (CSE) and high charge conductivity. Altermagnets are considered promising candidates for spin-splitting-torque MRAMs due to their vanishing net magnetic moment and the presence of spin-splitting bands. However, combining high CSE with high charge conductivity in altermagnetic materials has presented a significant challenge.
Approach
The study proposes and investigates the integration of Dirac cones into two-dimensional d-wave altermagnets. The intrinsic high carrier mobility associated with Dirac cones is leveraged to enable tunable charge and spin conductivities while maintaining high CSE. The methodology explores the role of Dirac-cone anisotropy in enhancing both CSE and charge conductivity. Additionally, cone tilting is introduced as an extra degree of tunability within this framework. This design principle guided the identification of specific materials and conditions.
Findings
- Introduction of Dirac cones into 2D d-wave altermagnets facilitates tunable charge and spin conductivities alongside high charge-to-spin conversion efficiency (CSE).
- Dirac-cone anisotropy serves as an effective mechanism for improving both CSE and charge conductivity.
- Cone tilting offers an additional tuning parameter for material properties.
- Guided by this design principle, a maximum CSE of 92% was identified in the material Cr2SeTeS.
- When the Fermi level is positioned slightly away from the Dirac point, a combination of high CSE, high charge conductivity, and the resulting high spin conductivity can be achieved simultaneously.
Why This Matters
This study contributes to the understanding of time-reversal-odd spin transport through the engineering of Dirac cones. It provides a practical pathway for the development of spin-source materials that integrate high charge conductivity with highly efficient charge-to-spin conversion. Such materials are relevant for applications requiring low critical charge-current density and low energy dissipation, particularly in the context of magnetic random-access memories.
Potential Applications
The findings indicate a route toward developing spin-source materials applicable in spin-splitting-torque magnetic random-access memories. These materials would feature high charge conductivity alongside highly efficient charge-to-spin conversion, addressing requirements for low critical charge-current density and low energy dissipation in such memory technologies.