Superconductivity

In the year of 1890 Heike Kemmerlingh Onnes in Leiden pioneered low temperature physics with his invention on the technique to liquefy Hydrogen and in 1906 to liquefy Helium. Initiated by this works, in 1911 he performed a study to observe the resistance of pure metals i.e. mercury at very low temperature (cryogenic). At that time, many believed that electrons flowing through a conductor would be completely halt at absolute zero temperature, or in other words the resistivity become infinitely large. The Result of Kammerlingh Onnes study stated that at the temperature of 4.2 K, the resistance of mercury is abruptly disappeared. He realized that there was a phase transition occurred and then he referred this phenomenon as “supraconductivity”, later adopted as “superconductivity.” We can safely describe superconductivity as a phenomenon where resistivity of several metals or alloys is disappeared at certain Temperature.

Fig. 0.1: Critical temperature of superconductor compared to normal metal

Numerous effort has been done to explain the phenomenon of superconductivity after its first discovery in 1911. From phenomenological macroscopic explanation to the microscopic explanation of BCS theory. Superconductor has several unique properties, that is; Magnetic field effect, Meissner effect, isotope effect. The Magnetic field effect can be described as disappearance of superconductivity under influence of magnetic field, there is critical value of magnetic field Hc in which above certain value superconductivity disappear. Superconductivity can be classified into two types based on its critical magnetic field; type I where there is only one critical field and type II where there are two critical field, the upper critical field Hc2 which separates normal phase from superconducting phase and the lower critical field Hc1 which separates superconducting mixed phase from the meissner phase, which is the same as the superconducting phase of type I. Continue reading “Superconductivity”

Science, physics and education

The application of science in modern world has produced many proven technology that can make human life easier, more comfortable, healthier, and safer. Science is a great gift for human being of all over time. With science, human managed to solve problems experienced in his/her life so as it able to improve the quality of his/her life. Beside, science is also one way to achieve objective truth. Physics is a science that deals with the interaction between physical phenomena and human as observer. It is a tool to explain the nature of physical world of the universe. Physics is very interesting because it can explain complex phenomena from microscopic world to the macroscopic world in simple, elegant and beautiful mathematical language.

Driven by curiosity, mankind is always zeal to know what really happened in physical world. Curiosity rises from the interaction between human sensory and environment or physical world where human are. Physics is always initiated by such interaction. From the interactions, various kind of information about physical units can be obtained. The interaction is not always a direct interaction between human sensory and physical phenomena, scientist often use instruments to help them to get information about the physical world which beyond the range of human sensory. Astrophysicist uses the telescope to obtain information about macroscopic world such as stars, planets, nebulas, etc. Solid State physicist uses electron microscope to obtain information and explore the microscopic world such as atom and electrons. From such interaction, physicist derives theories which provide systematic explanation of the interaction between physical phenomena. Theory brings physicist to develop some methods and certain process in order to confirm the truth behind phenomena that occurs. The confirmation of the truth between theory and experiments yields what we called knowledge. Continue reading “Science, physics and education”