The Difficulty of Maintaining Quantum Properties

"While two-dimensional (2D) materials exhibit remarkable functionalities with revolutionary potential, preserving their superior properties beyond the 2D limit remains a significant challenge," said Yinming Shao, assistant professor of physics at Penn State and lead author of the study. These atom-thin crystalline materials have diverse applications, ranging from flexible electronics to energy storage and quantum technologies.

Figure 1. Magnetism: A Breakthrough in Quantum Technology.

"Achieving, understanding, and controlling nanoscale confinement are therefore essential for advancing both quantum physics research and future quantum technologies." Figure 1 shows Magnetism: A Breakthrough in Quantum Technology.

Excitons: The Key to Quantum Advancement

The research team explored quasiparticles known as excitons, which possess unique optical properties and can transfer energy without carrying an electrical charge. These excitons were studied in a semiconductor material, a class of materials that conduct electricity under specific conditions while inhibiting it under others. Semiconductors are integral to modern technology, including computers, phones, and various electronics.

Excitons form when light strikes a semiconductor, energizing an electron to move to a higher energy level. The resulting excited electron and the hole it leaves behind together constitute an exciton. In conventional 3D semiconductors, like silicon, excitons are uniformly distributed.

“However, the binding energy of excitons in bulk materials like silicon is generally low, making them unstable and difficult to observe,” explained Yinming Shao, assistant professor of physics at Penn State and lead author of the study. He noted that excitons are most stable and demonstrate superior properties in 2D monolayers.

The Limitations of Conventional 2D Material Production

The standard method for producing 2D materials dates back to 2004 and led to the discovery of graphene, a single layer of carbon known for its high conductivity and remarkable strength. This technique, though simple, is labor-intensive, requiring individual layers to be exfoliated from a bulk crystal using adhesive tape.

In their thin 2D state, excitons can transfer energy without charge and emit light when their electron and hole recombine. This property is valuable for advanced optical applications. However, scaling up this process to produce large quantities of material while maintaining these properties remains a major challenge.

Harnessing Magnetism to Preserve Quantum Properties

At room temperature, CrSBr behaves like a typical semiconductor. However, cooling it to approximately -223 degrees Fahrenheit brings it to its ground state, the lowest energy state. In this state, CrSBr becomes an antiferromagnetic system, where the magnetic moments, or “spins,” of its particles align in a repeating pattern. Notably, in CrSBr, each layer alternates its magnetic alignment, canceling out the overall magnetic moment and making the material resistant to external magnetic forces.

This unique property confines excitons within layers of matching spin orientation rather than allowing them to migrate between layers with opposing spins, akin to vehicles on alternating one-way streets. These well-defined boundaries help maintain the integrity of excitons without requiring the peeling and stacking of individual layers.

“This approach effectively creates a single atomic layer within a bulk material while preserving a sharp interface,” Shao said. “It allows us to achieve the same exciton confinement seen in 2D materials without physical exfoliation.”

Experimental Validation of Magnetic Confinement

Using optical spectroscopy, theoretical modeling, and computational analysis, the researchers confirmed that magnetic confinement persisted regardless of the number of layers or the specific layer examined, including surface layers.

“We conducted extensive tests to verify this effect, and the results consistently held true,” Shao said.

A separate research team from Germany, led by Florian Dirnberger and Alexey Chernikov at TUD Dresden University of Technology, independently investigated the same magnetic semiconductor phenomenon. Upon comparing findings, both groups discovered their results aligned, reinforcing the validity of their conclusions.

“Our data matched remarkably well, despite using different crystal materials and conducting experiments in separate laboratories,” Shao noted. “Our results also align with theoretical predictions, leading us to publish this joint paper.”

A New Era for Quantum Technology

This breakthrough stems from integrating the principles of magnetism, Van der Waals interactions, and excitonic behavior to achieve quantum confinement. According to Shao, this discovery could have significant implications for advancing optical systems and quantum technologies.

Source: SciTECHDaily

Cite this article:

Priyadharshini S (2025),Magnetism Solves a Major Challenge in Quantum Technology, AnaTechmaz, pp. 208