Tsui << tsoo ee >> , Daniel Chee (1939-…), a Chinese-born American physicist, shared the 1998 Nobel Prize for physics with Robert Laughlin of the United States and Horst Störmer of Germany for their discovery of a new form of matter in which it seemed that electrons—the particles making up electric currents—had been divided into parts. Tsui made the discovery with Störmer, and Laughlin explained the results of their experiments.
Tsui was born on Feb. 28, 1939, in the province of Henan in China. With the help of Lutheran ministers, he moved to the United States in 1958. He received a Ph.D. degree in physics from the University of Chicago in 1967. His main research interest was the behavior of electrons in metals and semiconductors . He became a professor in the department of electrical engineering at Princeton University in New Jersey in 1982.
Tsui was working with Störmer at Bell Laboratories (then the research department of the Bell Telephone Company) in 1981 when he did his Nobel Prize winning work. The experimenters prepared an electrical component made of two different semiconductors—gallium arsenide and gallium aluminum arsenide—joined together. Using facilities at the Massachusetts Institute of Technology, they cooled the component to one-tenth of a Celsius degree above absolute zero (–273.15 °C) and placed it in a magnetic field that was one million times as strong as Earth’s.
Tsui and Störmer studied the quantum Hall effect at the point of contact between the two semiconductors. The Hall effect had been discovered by the American physicist Edwin Hall in 1879. In the Hall effect in ordinary metals, electric charges flowing through a magnetic field are pushed sideways, at right angles to the direction of the current and of the field, creating a measurable voltage at right angles to the current. In 1977, the German physicist Klaus von Klitzing presented a paper showing that as the intensity of a magnetic field increases, the strength of the Hall effect increases not continuously, but in steps. What Tsui and Störmer found was that, at lower temperatures and higher field strengths, there were more steps than those von Klitzing had discovered. Some of the steps corresponded to values of charge that seemed to be a fraction of the electron’s normal unit charge, such as 1/3, 2/5, 3/7, and so on.
