Researchers from the California Institute of Technology (Caltech) and Yale University, located in the United States, have developed an advanced method to calculate the Kondo effect with high accuracy. This phenomenon of quantum physics affects the electrical resistance of metals containing magnetic impurities.
This advancement allows for the anticipation of characteristics of real materials through fundamental theoretical calculations, initially eliminating the need for data obtained from experiments. The study was published in the journal Science and marks a significant progress in understanding materials whose electrons exhibit intricate behaviors.
In certain situations, the new methodology proved to be up to one hundred times more accurate than the simplified methods previously employed. Furthermore, this technique opens possibilities for investigating more elaborate materials, such as high-temperature superconductors.
Normally, the electrical resistance of metals tends to decrease as the temperature drops, facilitating electron movement. However, when the material contains small magnetic impurities, this pattern can change drastically. Below a specific temperature, called the Kondo temperature, the electrical resistance begins to increase again.
This occurs due to the interaction between the metal's electrons and those bound to the magnetic impurities. Such interactions have the potential to neutralize the magnetism of the atoms and, simultaneously, impede the flow of electric current.
Although the involved mechanisms were known to scientists, predicting the behavior of the Kondo effect with such a level of precision represented a major obstacle. The interaction between temperature, magnetism, and electronic properties occurs on minuscule scales, constituting a complex quantum problem known as the many-body problem.
Previously, researchers relied on simplified models and practical tests to estimate this phenomenon. However, these approaches failed to predict with the same accuracy how different compositions of metals and magnetic impurities would behave.
To overcome this restriction, the team implemented an approach known as 'ab initio,' which means 'from first principles.' This method uses the basic laws of quantum physics to determine a material's properties, rather than relying solely on approximations based on past observations.
The researchers integrated chemistry techniques to model a single magnetic atom in greater detail, treating it mathematically similarly to a larger molecule. Subsequently, they performed iterative calculations to refine predictions about electronic interactions.
The process demanded vast computational capacity and the use of sophisticated mathematical strategies to manage the system's complexity. By comparing the results with experimental measurements of the Kondo effect, the scientists confirmed that the method could replicate the materials' behavior with very high fidelity.
In some cases, the accuracy achieved by the approach exceeded that of simplified models by one hundredfold. This finding proves that calculations based on the basic principles of physics can predict specific characteristics of real materials.
Initial tests were conducted with relatively simple combinations of metals and magnetic impurities. The researchers view this phase as a starting point for studying more complex systems, where electronic interactions can generate properties that are difficult to explain or predict.
Potential areas of study include high-temperature superconductors and quantum magnetic materials. Superconductors have the ability to conduct electricity without resistance under certain conditions, generating great interest for applications in power grids and computing systems.
These materials often exhibit complex electronic behaviors, exactly the type of question that the new calculations can help investigate. The possibility of predicting their properties before conducting experiments can make the search for new materials much more focused.
Despite the promising results, the researchers still need to expand the method to handle more complex systems. The initial demonstration suggests that predicting the behavior of correlated electrons in real materials is becoming more feasible, although this does not mean that all quantum properties can be calculated with the same accuracy.
