Hong Kong University of Science and Technology team achieves 300x spin lifetime boost in perovskites

Introduction

A team from the Hong Kong University of Science and Technology (HKUST) has reported a dramatic increase—about 300 times—in the lifetime of spin polarization in perovskite semiconductors at room temperature. By engineering a chiral multiple‑quantum‑well (MQW) architecture, the researchers achieved a continuous "spin cascade" that suppresses the rapid decoherence normally caused by Rashba splitting. The work, published in Nature Photonics, suggests a practical pathway toward spin‑based optoelectronic and quantum devices that no longer require cryogenic cooling.

Chiral Multiple Quantum Wells: Design and Mechanism

Traditional perovskite spintronic platforms rely on single quantum wells, where spin information quickly decays at interfaces. HKUST’s approach replaces the single well with a stack of well‑oriented quantum wells, each possessing intrinsic chirality and slightly different thicknesses. This graded structure creates an energy landscape that guides spin‑polarized carriers through a series of intermediate states—a process the authors describe as a spin cascade.

Key aspects of the design include:

• Seed‑assisted crystallization: A two‑step growth method that yields highly ordered wells with controlled chirality across multiple perovskite phases.
• Energy gradient: Varying well widths generate a stepwise potential that drives spin transfer without the large Rashba fields that normally cause rapid dephasing.
• Chiral environment: The intrinsic handedness of each layer preserves spin orientation, allowing the polarization to survive far longer than in achiral structures.

The combined effect is a spin lifetime that persists for hundreds of nanoseconds at ambient conditions, a scale previously attainable only at temperatures near absolute zero.

Demonstrated Functionalities

Beyond the fundamental lifetime extension, the chiral MQW system exhibits several functional properties that underscore its technological relevance:

• High spin‑dependent charge transport: Measurements show charge carriers retaining over 80 % spin polarization during transport.
• Circularly polarized luminescence: The material emits light with a dissymmetry factor approaching 1.4 × 10⁻², indicating strong chiroptical activity.
• Proof‑of‑concept applications:

- X‑ray‑triggered dissymmetric photopolymerization: Leveraging the long‑lived spin states to drive asymmetric chemical reactions. - Circularly polarized light detection: Demonstrating a detector with enhanced sensitivity to the handedness of incoming photons.

These demonstrations hint at future uses in asymmetric photocatalysis, advanced optical sensing, and spin‑based information processing.

Implications for Quantum and Spintronic Technologies

The ability to maintain spin polarization at room temperature removes a major barrier for integrating spintronic components into practical devices. Potential impact areas include:

• Spin‑based qubits: Longer coherence times could simplify error‑correction schemes and reduce cooling overhead.
• Chiroptical photonics: Devices that manipulate light’s circular polarization for communication or imaging could benefit from the high dissymmetry factors.
• Spin‑tronic memory and logic: Extended lifetimes enable more robust spin‑current channels, paving the way for low‑power, non‑volatile memory architectures.

By providing a scalable, material‑level solution, the HKUST team’s chiral MQW platform may become a foundational building block for next‑generation quantum and spintronic systems.

Conclusion

HKUST’s chiral multiple‑quantum‑well perovskite represents a significant stride toward room‑temperature spintronic devices. The 300‑fold boost in spin lifetime, coupled with strong spin‑dependent transport and chiroptical emission, showcases a versatile platform that bridges fundamental materials science and practical quantum technologies. Continued exploration of this architecture could accelerate the development of spin‑based processors, sensors, and photonic components, bringing spintronics closer to everyday applications.