Converters & Calculators
Spin Hall Effect: Mechanism And Applications
Introduction
The Hall effect, traditionally associated with the generation of a voltage perpendicular to an electric current in a magnetic field, has developed into a phenomenon that includes the manipulation of electron spins. One such phenomenon is the Spin Hall effect (SHE), which plays a significant role in the field of spintronics. In contrast to the traditional Hall effect, the Spin Hall effect does not require an external magnetic field to generate spin currents, thereby providing a fundamental mechanism for the development of electronic devices in future research.
Mechanism of the Spin Hall Effect
The Spin Hall effect originates from intrinsic material properties and the spin–orbit coupling present therein. When an electric current passes through a non-magnetic conductor, spin–orbit interactions deflect electrons with opposite spins to opposing directions. This separation of spins results in the formation of a transverse spin current.
Key Factors Influencing the SHE
- Material composition: Heavy metals such as platinum and tungsten exhibit strong spin–orbit coupling, which enhances the SHE.
- Temperature: Lower temperatures reduce phonon scattering, thereby increasing the efficiency of the spin current.
- Layer thickness: The thickness of the conducting layer influences the magnitude of the generated spin current.
Applications of the Spin Hall Effect
The capacity to generate and control spin currents without the need for an external magnetic field offers several technical applications:
Spintronic Devices
Spintronics utilises the spin of electrons in addition to their charge for information processing. SHE enables the production of spin-based transistors and storage devices that operate with lower power consumption and enhanced operational speed compared to conventional electronics.
Magnetic Storage
The Spin Hall effect facilitates the manipulation of magnetic domains in storage devices. This property supports the development of magnetic random access memory (MRAM) with improved integration density and operational performance.
Quantum Computing
The Spin Hall effect contributes to the stabilisation and control of qubits in quantum computers, thereby increasing coherence times and operational reliability.
Parameters of the Spin Hall Effect
|
Parameter |
Description |
Typical values |
|
Spin Hall angle |
Efficiency of converting electrical current into a spin current |
0.1 – 0.2 |
|
Specific resistance |
Electrical resistance of the material |
10 – 100 μΩ-cm |
|
Spin diffusion length |
Distance over which the spin current is maintained |
1 – 10 nm |
|
Critical current density |
Current density required to generate a spin current |
1 000 000 – 100 000 000 A/m² |
|
Temperature range |
Operating temperature range for SHE devices |
4 K – 300 K |
Further information can be found at Stanford Advanced Materials (SAM).
Frequently Asked Questions
What is the Spin Hall effect?
The Spin Hall effect is a phenomenon whereby an electric current in a conductor results in a transverse spin current due to spin–orbit coupling. This process separates electron spins across the material.
How does the Spin Hall effect differ from the traditional Hall effect?
Unlike the traditional Hall effect, which requires an external magnetic field to generate a perpendicular voltage, the Spin Hall effect derives from intrinsic spin–orbit interactions and does not depend on an external magnetic field.
Which materials are most suitable for observing the Spin Hall effect?
Materials with strong spin–orbit coupling, such as platinum, tungsten and certain topological insulators, are deemed appropriate for observing a measurable Spin Hall effect.
What are the primary applications of the Spin Hall effect?
The Spin Hall effect is used primarily in spintronic devices and magnetic storage technologies and is under investigation for its role in quantum computing applications.
What challenges must be addressed for the wide application of devices based on the Spin Hall effect?
Key challenges include identifying materials with optimal properties, developing scalable manufacturing processes and integrating spintronic components into existing electronic systems.
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