Department of Condensed Matter

Dan Shahar
  Email: dan.shahar@weizmann.ac.il
  Title: Associate Professor
  Tel: +972-8-934-2575
  Fax: +972-8-934-4477
  Building: Braun
  Room: C211 		Dan Shahar

 Research Interests:

We use top-quality GaAs-based semiconducting systems to learn about the behavior of the electrons buried in them, under conditions where these electrons are forced to strongly interact with their neighbors. These conditions, which prevail at low temperatures, have yielded the peculiar state of the 'fractional quantum Hall effect', whose discoverers were awarded the Nobel Prize in physics this year. The strong interaction between the charge carriers have been shown to fundamentally alter many properties of the system. For example, a topic in which we are currently investing most of our efforts, is the appearance of an unexpected metallic phase of two-dimensional electrons, a state which is (nearly) forbidden for non-interacting electrons.

Of particular interest to us are a new type of phase transitions, termed 'quantum' phase transitions, which are analogous to regular, thermodynamic phase transitions (evaporation of water, for example) except for the fact that they (theoretically) take place at the absolute zero of temperatures. As such, their nature is completely dominated by quantum mechanics.

For these studies we utilize a state-of-the-art refrigerator capable of achieving temperatures of a few thousands of a degree above the absolute zero. This 'dilution' type refrigerator uses a subtle quantum effect to reach these low temperatures. The system is designed with flexibility and ease of operation as top priorities, and can be used in research on a large diversity of physics problems, from superconductivity to organic conductors, carbon nanotubes etc.

 References:

  1. M. Hilke, D.Shahar, S.H. Song, D.C. Tsui, Y.H. Xie, and Don Monroe,'The quantized Hall insulator: A new insulator in two-dimensions', Nature, 15 Oct. 1998.

  2. Y. Hanein, U. Meirav, D. Shahar, C.C. Li, D.C. Tsui, and Hadas Shtrikman, 'The metallic-like conductivity of a two-dimensional hole system', Physical Review Letters 80, 1288 (1998).

  3. S.L. Sondhi, S.M. Girvin, J.P. Carini and D. Shahar, 'Continuous quantum phase transitions', Review of Modern Physics 69, 315 (1997).