Giant Orbital Hall Effect in Silicon: A New Era for Energy-Efficient Spintronics

Read Below:  

• Giant OHE discovery in CMOS-grade silicon defies spintronics conventions, outperforming platinum in torque efficiency and operating at room temperature using standard Si/NiFe structures. 

• Seamless CMOS integration of orbital torque logic and MRAM devices is now possible—silicon enables logic-in-memory systems without exotic materials or cryogenic support. 

• McKinsey Electronics supports spintronic innovation in the ATME region, providing advanced components and design guidance to help OEMs commercialize silicon-based SOT-MRAM and AI edge devices. 

Recent discoveries have revealed a giant orbital Hall effect (OHE) in silicon (Si) at room temperature, representing an unexpected breakthrough in spintronics. This finding defies the conventional wisdom that only heavy metals with strong spin-orbit coupling can generate substantial orbital angular momentum. The results show silicon, a light and CMOS-compatible semiconductor, can outperform even platinum in torque efficiency. This blog analyzes the theoretical basis, experimental findings, quantitative comparisons and future implications of this discovery.

What Is the Orbital Hall Effect and Why Silicon Is a Game-Changer

The orbital Hall effect (OHE) refers to the generation of a transverse flow of orbital angular momentum when an electric field is applied. Unlike the spin Hall effect (SHE), which involves spin currents, OHE leverages orbital degrees of freedom, offering a new route to manipulate magnetic states without relying on heavy atoms or high spin-orbit coupling (SOC).

This makes silicon's giant OHE especially surprising. Being a light element with weak SOC, silicon was never considered a candidate for significant orbital current generation. Yet, its high orbital torque efficiency and room-temperature operation reveal a promising new direction in the field of orbitronics.

Theoretical Background: Why OHE Works in Silicon

The key to understanding OHE in Si lies in:

• Orbital hybridization: The mixing of p-orbitals and conduction states enhances orbital momentum transport.

• Berry curvature effects: Silicon’s band structure supports non-trivial orbital Berry curvatures that facilitate angular momentum flow.

• Crystal symmetry: The cubic symmetry of silicon’s lattice enhances transverse momentum transport, even in the absence of strong SOC.

  
  

These mechanisms allow silicon to generate large orbital currents, decoupled from spin-orbit effects.

Key Experimental Findings

1. Giant OHE in CMOS-Compatible Silicon

Recent experiments have shown that silicon’s orbital Hall conductivity can reach ~300–500 Ω⁻¹cm⁻¹, which surpasses even platinum (Pt) at ~250 Ω⁻¹cm⁻¹. These measurements were validated using layer structures such as Si/NiFe, showing clear transverse voltages and torque-induced switching.

2. Enhanced Orbital Torque Efficiency

Silicon exhibits a torque efficiency 2–3 times higher than Pt. This means it can convert charge currents into orbital angular momentum far more efficiently, reducing the energy needed for switching operations in magnetic devices.

3. Room Temperature Operation

Crucially, all demonstrations were conducted at room temperature, ensuring immediate relevance for industrial applications. No cryogenic support or exotic materials are needed.

Quantitative Comparison of OHE Materials

Integration with CMOS Processes

One of the strongest advantages of using silicon for OHE-based devices is seamless compatibility with existing CMOS fabrication:

• Front-End-of-Line (FEOL) integration without needing new materials.

• Monolithic integration with logic layers for logic-in-memory designs.

• Potential reduction in Back-End-of-Line (BEOL) complexity.

This allows for MRAM and spin-logic devices to be built directly on mainstream silicon platforms without exotic process adaptations.

Practical Device Demonstrations

Several lab prototypes have demonstrated:

• Orbital torque-induced magnetization switching in Si/NiFe bilayers

• Repeatable, low-noise switching at room temperature

• Lower switching currents compared to Pt-based stacks

  
  

These results confirm silicon’s practical viability in spintronic memory and logic applications.

Applications of Silicon OHE in Next-Generation Electronics

The implications of these findings are broad:

• Spin-Orbit Torque MRAM (SOT-MRAM): Enables ultra-low power, high-endurance memory with standard silicon substrates.

• Spin-Logic Circuits: Silicon can now drive spin-based logic without relying on rare materials.

• Neuromorphic and AI Edge Devices: Integration of memory and logic in the same layer using standard process nodes.

• Low-Power IoT: Silicon-based spintronics can drastically reduce standby power in edge computing chips.

Future Outlook and Commercial Impact

This discovery shifts the design theory for spintronics:

• New research is now focused on using other light semiconductors (e.g., Ge, GaAs) for OHE.

• Industry interest is growing around silicon-based spin-logic co-processors.

• The SOT-MRAM market is expected to benefit from faster commercialization via CMOS-compatible OHE materials.

Expert Insight

“This shows that we can rethink the design rules for spintronic devices using mainstream semiconductors. It’s not just about heavy elements anymore, orbital transport can unlock new frontiers,” says Dr. R. Matsumoto, lead author of the breakthrough study.

The recent discovery of a giant orbital Hall effect (OHE) in silicon marks a pivotal shift in the trajectory of spintronics, especially for industries prioritizing energy efficiency and CMOS integration. For companies designing next-generation memory or logic devices in the GCC, this opens new possibilities for using widely available, cost-effective silicon in applications traditionally dominated by heavy metals. Headquartered in Dubai and serving the wider ATME region, McKinsey Electronics supports this transition by offering access to tier-one components and on-ground technical engineering support for spintronic and CMOS-based innovation. Our proximity to leading-edge development in the Gulf positions us to help engineers and system designers evaluate and adopt advanced materials in real-world, production-ready platforms.

Contact us today.