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Ayvar GiaeverAmerican physicist
Date of Birth: 05.04.1929
Country:  USA |
Content:
- Ivar Giaever: Norwegian-American Nobel Prize Winner in Physics
- Military Service and Emigration
- Research at General Electric
- Tunneling and Superconductivity
- Josephson Effects
- Nobel Prize and Later Work
- Personal Life and Awards
Ivar Giaever: Norwegian-American Nobel Prize Winner in Physics
Early Life and EducationIvar Giaever was born on April 5, 1929, in Bergen, Norway. He was the second of three children born to John A. Giaever, a pharmacist, and Gudrun M. Skårud. Giaever attended primary school in Toten and secondary school in Hamar. After graduating from high school in 1946, he worked for a year at the Raufoss ammunition factory. In 1948, he enrolled at the Norwegian Institute of Technology in Trondheim, graduating in 1952 with a degree in mechanical engineering.
Military Service and Emigration
Upon graduating, Giaever was drafted into the Norwegian army and served as a corporal for one year. After being discharged, he worked as an examiner at the Norwegian Patent Office. In 1954, due to housing shortages in Norway, Giaever emigrated to Canada, where he briefly worked as an architectural draftsman before taking a job as a mechanical engineer for General Electric Company's Fundamental Engineering Program.
Research at General Electric
In 1956, Giaever joined General Electric's Research and Development Center in Schenectady, New York, where he worked on applied mathematics problems. It was at Schenectady that Giaever's interest in physics was sparked. He joined the solid-state physics research group in 1956 and simultaneously pursued graduate studies at the Rensselaer Polytechnic Institute.
Giaever's research at General Electric focused on the electrical behavior of junctions consisting of metal contacts separated by very thin insulating layers. This work was of commercial interest because the surfaces of most electrical metal contacts are separated by thin insulating layers of oxides and contaminants.
Tunneling and Superconductivity
Classical physics predicted that in cases where the voltage between two contacts is not high enough for electrons to overcome the electrical barrier created by the insulator, no current would flow, as there would be no electrons with sufficient energy to penetrate the insulator. However, quantum mechanics, which describes the behavior of systems at the atomic or subatomic scale, suggests that if the insulating film is thin enough, an electron can "tunnel" through it and appear on the other side of the barrier.
Japanese physicist Leo Esaki had invented a diode (known as the tunnel diode or Esaki diode) in which the electrical junctions are so thin (about a billionth of a meter thick) that electrons can tunnel through them, giving rise to unusual and useful electrical properties.
While pursuing his graduate studies, Giaever became familiar with the BCS theory of superconductivity, named after John Bardeen, Leon N. Cooper, and J. Robert Schrieffer. In the superconducting state, observed in some metals and metallic compounds, materials completely lose their resistance when cooled below critical temperatures close to absolute zero, and electric currents can flow through them without loss. The critical temperature of a material depends on its chemical composition and structure.
Bardeen, Cooper, and Schrieffer showed in 1957 that superconductivity in a material is governed by the interaction of pairs of electrons mediated by the exchange of atomic vibrations (phonons). This hypothesis led to the development of the BCS theory, the principal theory of superconductivity. According to this theory, electron interactions with atomic vibrations in a material give rise to so-called energy gaps for electrons in the superconductor, i.e., the electrons in superconductors are not allowed to have these energies.
Giaever set out to determine experimentally whether the presence of energy gaps in superconductors would affect the electrical properties of a junction consisting of an insulator between a normal metal and a superconductor. He found that the energy gap was readily observable and measurable using a technique he developed. This provided strong confirmation of the BCS theory.
Further studies of thin films of aluminum separated by a layer of aluminum oxide showed that the electrical properties of such junctions could provide a wealth of information about the characteristics of atomic vibrations and the behavior of superconductors, giving insights that would have been difficult to obtain by any other means. Giaever's tunneling method quickly became one of the principal ways of probing and characterizing superconductors.
Josephson Effects
In 1962, Brian D. Josephson extended Giaever's ideas to the case of a junction consisting of an insulator between two superconductors. Josephson proposed that currents could flow between the two superconductors even in the absence of a voltage across them, and that a voltage applied to the junction would give rise to an alternating current at a very high frequency (Josephson effects). Josephson's theory led to the development of extremely sensitive detectors of changes in magnetic field and voltage. Devices based on Josephson effects are used in high-speed, low-power logic circuits in computers.
Nobel Prize and Later Work
Giaever received his doctorate in 1964 and became a United States citizen the same year. In 1973, Giaever and Leo Esaki were awarded half of the Nobel Prize in Physics "for their experimental discoveries regarding tunneling phenomena in semiconductors and superconductors." The other half was awarded to Josephson. In his presentation speech at the Nobel Prize ceremony, Stig Lundqvist of the Royal Swedish Academy of Sciences stated that the three new laureates "have opened up new fields of research in physics. These fields are closely interconnected, since the pioneering work of Esaki provided the basis for and directly stimulated the discovery made by Giaever, which in turn has acted as a stimulus leading to the theoretical predictions by Josephson... The discoveries of the laureates have found rapid applications in electronics, in detection of gravitational waves, in geological prospecting for ore, in transmission of messages through water and rock, and in studying the electromagnetic field around the heart and brain."
In his acceptance speech, Giaever stated that "the road to scientific discovery is seldom straightforward and does not necessarily require a deep background and skill. I am convinced that the beginner often has an advantage over the expert precisely because of his ignorance; he does not realize all the complicated reasons why it is impossible to try a silly experiment." However, Giaever added, "it is essential to have access to timely advice and help from experts in various fields. I was at the right place at the right time and... I made friends who helped me unselfishly."
With a Guggenheim Fellowship, Giaever spent 1970 at Cambridge University studying biophysics and then returned to General Electric. His subsequent research focused on the properties of cell membranes and the behavior of protein molecules on solid surfaces. Giaever's final work in immunology was carried out at General Electric and the Albany Medical Center.
Personal Life and Awards
Giaever married Inger Skramstad in 1952, and they had four children. An outdoor and sports enthusiast, Giaever enjoys tennis, hiking, travel, skiing, sailing, and windsurfing.
In 1965, Giaever was awarded the American Physical Society's Oliver E. Buckley Prize for Solid State Physics. He is a member of the U.S. National Academy of Sciences, the Institute of Electrical and Electronics Engineers, the Norwegian Academy of Sciences, the Biophysical Society, and the American Physical Society.
