Superconductivity: A Journey through the Quantum World
The phenomenon of superconductivity was first observed in 1911 at the University of Leiden in the Netherlands by the physicist Heike Kamerlingh Onnes. He subjected gaseous helium to cycles of cooling and observed that the electrical resistance of certain materials decreased abruptly when cooled to temperatures near 4.2K (critical temperature). This was a breakthrough as it contradicted the idea that resistance would be infinite when electrons were “frozen.”
This achievement earned Onnes the Nobel Prize in 1913 and attracted scientists to study the phenomenon at the University of Leiden. By 1933, superconducting materials had been discovered, but the understanding of the phenomenon was still limited. In 1933, Meissner and Ochsenfeld observed the “Meissner Effect,” in which a superconductor expels magnetic field lines from its interior.
In 1935, the London brothers satisfactorily described the Meissner Effect and developed the London Theory, which mathematically described the effect but didn’t explain its cause. Superconductivity was classified into Type I and Type II, with different behaviors regarding magnetic fields.
The theory that explained the phenomenon was developed by John Bardeen, Leon N. Cooper, and John R. Schrieffer in the 1950s and was called the BCS Theory. This theory described the attraction between electrons mediated by phonons (collective atomic vibrations).
In 1986, a ceramic material, LBCO, was discovered to exhibit superconductivity at a higher temperature, challenging previously accepted limits. This raised questions about the theory of critical temperature.
Currently, there isn’t a fully satisfactory theory to explain high-temperature superconductivity. The article is written by Rieli Tainá Gomes dos Santos and references various sources, including scientific articles.
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Summary
Superconductivity, a fascinating phenomenon in physics, was discovered in 1911 by physicist Heike Kamerlingh Onnes at the University of Leiden in the Netherlands. This article revisits the history of superconductivity, from its initial observations to the theoretical and experimental advancements that have shaped our understanding of this unique state of matter. We discuss the evolution of theories explaining the phenomenon, from the London Theory to the revolutionary BCS Theory developed by John Bardeen, Leon N. Cooper, and John R. Schrieffer. We explore different types of superconductors, highlighting the differences between Type I and Type II superconductors.
Keywords: Superconductivity, BCS Theory, Meissner Effect, London Theory, electrical conductivity.
Introduction
Superconductivity, a phenomenon where certain materials conduct electricity without electrical resistance, has continued to intrigue the scientific community since its discovery in 1911 by Heike Kamerlingh Onnes at the University of Leiden. This phenomenon challenges conventional understanding of electrical conductivity and holds significant implications for technological applications in fields such as electronics and energy. In this article, we will explore the history of superconductivity, from its historical roots to contemporary theories that seek to explain its properties.
1. The Journey of Discovery
Heike Kamerlingh Onnes was a pioneer in observing superconductivity, using ultralow temperatures to investigate the electrical properties of materials. His experiments with mercury revealed the sharp drop in electrical resistance when the metal was cooled to temperatures near 4.2 K, known as the critical temperature. The discovery led Onnes to be awarded the Nobel Prize in 1913, and his research triggered growing interest in superconductivity among scientists worldwide.
2. Explanatory Theories
The London Theory, developed by Fritz and Heinz London, offered a mathematical description of the Meissner Effect, in which a superconductor expels magnetic field lines. However, this theory didn’t explain the origin of the phenomenon. The BCS Theory, formulated by Bardeen, Cooper, and Schrieffer, provided a deeper explanation. It proposed that electrons form Cooper pairs due to interaction with phonons, which are collective vibrations in the atoms of the crystal lattice. These pairs can flow without electrical resistance, resulting in superconductivity.
3. Challenges and Advances
The development of the BCS Theory propelled our understanding of superconductivity, but limitations were still apparent. The discovery of high-temperature superconducting materials in 1986 challenged expectations, leading to a search for a theory that could explain superconductivity at higher temperatures. This search continues to this day, with the scientific community seeking to understand the underlying mechanisms of superconductivity under diverse conditions.
Conclusion
Superconductivity remains an active area of research, with both theoretical and practical implications. Its history is marked by experimental and theoretical breakthroughs that have led us to a deeper understanding of the quantum behavior of materials. As we explore the mysteries of superconductivity, we can envision a future where its applications will revolutionize technology and our understanding of the nature of matter.
References
GOMES DOS SANTOS, Rieli Tainá. Breve história da supercondutividade. GPET Física, 2022. Available at: https://www3.unicentro.br/petfisica/2022/05/05/breve-historia-da-supercondutividade/. Accessed on August 16, 2023.
