Scientists Can Now Predict a Mysterious Quantum Effect in Real Materials With Unprecedented Accuracy

For decades, scientists have struggled to accurately predict how certain materials behave when electrons interact in complex ways. Now, researchers from the California Institute of Technology (Caltech) and Yale University have developed a powerful new computational method that could change how scientists understand and design advanced materials.

The breakthrough focuses on the Kondo effect, a strange quantum phenomenon that occurs when magnetic atoms are embedded inside metals. Using a new approach based on the actual atomic and electronic structures of materials, researchers can calculate this effect much more accurately than many traditional methods.

Published in the journal Science, the research marks an important step toward predicting the behavior of complicated quantum materials using computer simulations rather than relying entirely on experimental measurements.

In the future, this approach could help scientists investigate materials with unusual properties, including those associated with high-temperature superconductivity and advanced quantum technologies.

What Is the Kondo Effect?

The Kondo effect is a quantum phenomenon that changes the electrical resistance of a metal containing small amounts of magnetic impurities.

To understand it, imagine a piece of copper containing a tiny number of iron or manganese atoms. These foreign atoms possess magnetic properties because of the behavior of their electrons.

Normally, when a metal cools down, its electrical resistance decreases. This happens because the movement of electrons becomes less affected by certain types of thermal disturbances.

However, metals containing magnetic impurities can behave differently.

When the temperature falls below a particular point, known as the Kondo temperature, the electrical resistance stops decreasing as expected. Instead, it reaches a minimum and then begins to rise again as the material becomes colder.

This unusual change is known as the Kondo effect.

The reason lies in the interaction between the magnetic impurity and the electrons moving through the surrounding metal. These interactions change how electrons scatter through the material, producing the unexpected increase in resistance.

Although the phenomenon may sound simple, explaining it accurately requires scientists to understand the collective behavior of many interacting electrons.

How Do Electrons Hide an Atom's Magnetism?

The Kondo effect becomes easier to understand by looking at what happens around a magnetic atom.

Magnetic atoms contain unpaired electrons whose spins give them their magnetic properties. At relatively high temperatures, the atom's magnetic moment can fluctuate without being strongly controlled by the surrounding electrons.

As the material cools, electrons in the metal begin interacting more strongly with the magnetic impurity.

Through quantum interactions, these surrounding electrons can partially screen the impurity's magnetic moment. In simple terms, they form a collective cloud that reduces the observable magnetism of the embedded atom.

This process is called Kondo screening.

However, these interactions also influence how electrons move through the metal. The additional scattering contributes to the unusual change in electrical resistance that defines the Kondo effect.

The challenge is that the behavior cannot be understood by examining a single electron in isolation. Scientists must account for the combined influence of many electrons interacting with one another.

That makes the Kondo effect a classic example of a quantum many-body problem.

Why Has Predicting the Kondo Effect Been So Difficult?

Scientists have studied the Kondo effect for decades, and its basic physical explanation is well established. The difficult part has been predicting exactly how it will appear in a specific real material.

Traditional computational methods often simplify a material's electronic structure. Researchers may focus on a limited number of electron orbitals and use mathematical models to approximate the interactions within the system.

These simplified models are valuable because they make difficult quantum calculations more manageable. However, they can miss important details of the actual material.

Real materials contain complicated arrangements of atoms and electrons. Their properties depend on chemical composition, electronic structure and the interactions between particles.

As a result, a model that works well for one material may not accurately predict the behavior of another.

For many years, scientists could describe the general features of the Kondo effect but struggled to calculate its precise behavior in specific materials from first principles.

Being able to make such predictions would be extremely useful. Researchers could identify promising materials computationally before investing time and resources in laboratory experiments.

A New Approach Based on Real Atomic Structures

To overcome this challenge, the Caltech and Yale research team adapted highly accurate computational techniques originally developed for quantum chemistry.

Quantum chemistry methods are designed to describe the behavior of electrons in atoms and molecules. The researchers applied these tools to magnetic impurities inside metals, treating the impurities in a way that preserves much more of their actual electronic complexity.

Rather than depending entirely on simplified models, the approach uses detailed information about the material's atomic and electronic structure to calculate the relevant quantum interactions.

This allows researchers to study how electrons interact with magnetic impurities more faithfully.

The research was led by Tianyu Zhu and Linqing Peng, who began working on the project in the laboratory of Garnet Kin-Lic Chan, a professor of chemistry at Caltech and a leading researcher in computational quantum chemistry.

The team reported its findings in a Science paper titled Toward an exact quantum many-body treatment of Kondo correlation in magnetic impurities.

The method does not eliminate every challenge associated with quantum calculations. However, it offers a more accurate way to tackle an important problem that has long tested theoretical physics and computational chemistry.

Calculations Up to 100 Times More Accurate

To evaluate their approach, the researchers studied seven different transition-metal atoms embedded in copper.

Transition metals are particularly interesting because their electronic structures can produce complex magnetic and quantum behavior.

The team compared its calculations with predictions obtained using conventional model-based techniques.

For most of the elements studied, the new method achieved accuracy improvements of up to two orders of magnitude, equivalent to approximately 100 times better accuracy by the comparison used in the research.

This is a significant advance because it demonstrates that detailed, material-specific quantum predictions can become more practical without relying exclusively on simplified descriptions of electronic interactions.

The findings also suggest that computational methods can help scientists investigate complicated materials with greater confidence.

Instead of simply describing what experiments have already revealed, researchers may increasingly be able to predict certain material properties before conducting experiments.

Could This Help Scientists Discover Better Superconductors?

One of the most exciting potential applications is the study of strongly correlated quantum materials.

In ordinary materials, scientists can often approximate the behavior of electrons without accounting for every interaction between them. In strongly correlated materials, however, the behavior of one electron can depend heavily on what other electrons are doing.

These interactions can produce unusual properties that are difficult to explain using conventional theories.

High-temperature superconductors are an important example. Superconductors can carry electrical current without ordinary electrical resistance under suitable conditions, but understanding the mechanisms behind high-temperature superconductivity remains a major scientific challenge.

The new method does not directly solve the mystery of high-temperature superconductivity. The Kondo effect is a different quantum phenomenon, and the systems studied in this research are simpler than many superconducting materials.

Nevertheless, accurately predicting the Kondo effect provides a valuable testing ground for computational techniques that could eventually be extended to more complicated quantum systems.

If researchers can develop similarly reliable methods for larger and more complex materials, they may be able to screen potential candidates for new superconductors, quantum magnets and other advanced materials using computer simulations.

This could help narrow the search for materials with useful properties and guide experimental researchers toward the most promising candidates.

A Step Toward Predicting Materials Before Making Them

The research represents an important step toward a future in which scientists can predict certain properties of real materials directly from their fundamental atomic and electronic structures.

Such capabilities could improve the way researchers study magnetic materials, design quantum technologies and investigate systems where electron interactions produce unexpected behavior.

However, much work remains before these methods can be applied reliably to every complex material. More advanced quantum systems may require greater computational resources and additional methodological improvements.

For now, the Kondo effect provides a crucial demonstration of what accurate quantum simulations can achieve.

By moving beyond simplified models and capturing more of the complexity of real materials, researchers are bringing predictive materials science closer to reality.

The long-term goal is ambitious: to use powerful calculations to identify materials with valuable properties before they are produced in a laboratory. If that goal becomes achievable across a broader range of quantum materials, it could transform how scientists search for the next generation of electronic, magnetic and superconducting technologies.

Reference:

1. Tianyu Zhu, Linqing Peng, Huanchen Zhai, Zhi-Hao Cui, Runze Chi, Garnet Kin-Lic Chan. Toward an exact quantum many-body treatment of Kondo correlation in magnetic impurities. Science, 2026; 393 (6810): 522 DOI: 10.1126/science.adq7402