Department of Condensed Matter

Vladimir Umansky
  Email: vladimir.umansky@weizmann.ac.il
  Title: Senior Staff Scientist
  Tel: +972-8-934-2571
  Fax: +972-8-934-4477
  Building: Braun
  Room: C209 		Vladimir Umansky

 Research Interests:

 Publications:

  1. M. Avinun-Kalish, M. Heiblum, O. Zarchin, D. Mahalu, V. Umansky, Crossover from 'mesoscopic' to 'universal' phase for electron transmission in quantum dots, NATURE 436, 529-533 (2005).

  2. M. C. Geisler, J.H. Smet, V. Umansky, K. von Klitzing, B. Naundorf, R. Ketzmerick, H. Schweizer, Detection of a Landau band-coupling-induced rearrangement of the Hofstadter butterfly, Phys. Rev. Lett. 92, 256801 (2004).

  3. J. Martin, S. Ilani, B. Verdene, J. Smet, V. Umansky, D. Mahalu, D. Schuh, G. Abstreiter G, A. Yacoby. Localization of fractionally charged quasi-particles, SCIENCE 305 (5686): 980-983 AUG 13 (2004).

  4. M. Rahm, R. Hollinger, V. Umansky, D. Weiss, Influence of point defects on magnetic vortex structures. J.Appl. Phys. 95 (11), 6708-6710 (2004).

  5. R.G. Mani, J.H. Smet, K. von Klitzing, V. Narayanamurti, W.B. Johnson, V. Umansky, Radiation-induced oscillatory magnetoresistance as a sensitive probe of the zero-field spin-splitting in high-mobility GaAs/AlxGa1-xAs devices, Phys. Rev. B 69 (19), 193304 (2004).

  6. R.G. Mani, J.H. Smet, K. von Klitzing, V. Narayanamurti, W.B. Johnson, V. Umansky, Demonstration of a 1/4-cycle phase shift in the radiation-induced oscillatory magnetoresistance in GaAs/AlGaAs devices, Phys. Rev. Lett. 92, 146801 (2004).

  7. R. G. Mani, V. Narayanamurti, K. von Klitzing, J.H. Smet, W.B. Johnson, V. Umansky, Radiation-induced oscillatory Hall effect in high-mobility GaAs/AlxGa1-xAs devices, Phys. Rev. B 69 (16), 161306 (2004).

  8. M. Avinun-Kalish, M. Heiblum, A. Silva, D. Mahalu, V. Umansky, Controlled dephasing of a quantum dot in the Kondo regime, Phys. Rev. Lett. 92, 156801 (2004).

  9. S.Ilani, J. Martin, E. Teitelbaum, J.H. Smet, D. Mahalu, V. Umansky, A. Yacoby, The microscopic nature of localization in the quantum Hall effect, NATURE, 427, 328-332 (2004).

  10. C. Albrecht, J.H. Smet , K. von Klitzing, D. Weiss, V. Umansky , H. Schweizer, Evidence of Hofstadter's fractal energy spectrum in the quantized Hall conductance, PHYSICA E, 20 (1-2), 143-148 (2003).

  11. Y.C. Chung, M. Heiblum, V. Umansky, Scattering of bunched fractionally charged quasiparticles, Phys. Rev. Lett. 91, 216804 (2003).

  12. S.K. Watson , R.M. Potok, C.M. Marcus, V. Umansky . Experimental realization of a quantum spin pump, Phys. Rev. Lett. 91, 258301 (2003).

  13. M. Rahm, J. Biberger, V. Umansky, D. Weiss, Vortex pinning at individual defects in magnetic nanodisks, J. Appl. Phys. 93 (10), 7429-7431 ( 2003).

  14. M. Rahm, M. Schneider, J. Biberger, R. Pulwey, J. Zweck, D. Weiss, V. Umansky, Vortex nucleation in submicrometer ferromagnetic disks, Appl. Phys. Lett. 82 (23), 4110-4112 (2003).

  15. Y.C. Chung, M. Heiblum, Y. Oreg, V. Umansky, D. Mahalu. Anomalous chiral Luttinger liquid behavior of diluted fractionally charged quasiparticles, Phys. Rev. B 67 (20), 201104 (2003).

  16. R.M. Potok, J.A. Folk, C.M. Marcus, V. Umansky, M. Hanson, A.C. Gossard . Spin and polarized current from Coulomb blockaded quantum dots. Phys. Rev. Lett. 91, 016802 (2003).

  17. J. A Folk, R. M. Potok, C. M. Marcus,., & V. Umansky. A gate-controlled bidirectional spin filter using quantum coherence. Science 299, 679 (2003).

  18. R. M. Potok, J. A. Folk, C. M. Marcus, &Mp; V. Umansky. Detecting spin-polarized currents in ballistic nanostructures. Phys. Rev. Lett. 89, 266602 (2002).

  19. R.G. Mani, J.H. Smet, K. von Klitzing, V. Narayanamurti, W.B. Johnson , V. Umansky, Zero-resistance states induced by electromagnetic-wave excitation in GaAs/AlGaAs heterostructures, NATURE 420, 646-650 (2002).

  20. E. Comforti, Y.C. Chung, M. Heiblum, V. Umansky, Multiple scattering of fractionally charged quasiparticles, Phys. Rev. Lett. 89, 066803 (2002).

  21. E. Comforti, Y.C. Chung, M. Heiblum, V. Umansky, .D. Mahalu, Bunching of fractionally charged quasiparticles tunnelling through high-potential barriers, NATURE 416, 515-518 (2002).

  22. Y. Yayon, M. Rappaport, V. Umansky, I. Bar-Joseph , Anisotropy and periodicity in the density distribution of electrons in a quantum well, Phys. Rev. B 66, 033310 (2002).

  23. Y. Yayon, A. Esser, M. Rappaport, V. Umansky, H. Shtrikman, I. Bar-Joseph , Long-range spatial correlations in the exciton energy distribution in GaAs/AlGaAs quantum wells, Phys. Rev. Lett. 89, 157402 (2002).

  24. Y. Yayon, M. Rappaport, V. Umansky, I. Bar-Joseph, The microscopic origin of the exciton-charged exciton spectrum, Phys. Stat. Sol. A-Applied Research, 190 (3): 607-614 (2002).

  25. S.M. Cronenwett, H.J. Lynch, D. Goldhaber-Gordon, L.P. Kouwenhoven, C.M. Marcus, K. Hirose, N.S. Wingreen, V. Umansky, Low-temperature fate of the 0.7 structure in a point contact: A Kondo-like correlated state in an open system, Phys. Rev.Lett. 88, 226805 (2002).

  26. L.V. Kulik, I.V. Kukushkin, V.E. Kirpichev, J.H. Smet, K. von Klitzing, V. Umansky, W. Wegscheider, Cyclotron spin-flip excitations in the 2D-electron system, PHYSICA E, 12 (1-4): 574-577 (2002).

  27. B.M. Ashkinadze, V. Voznyy, E. Cohen, A. Ron, V. Umansky, Magnetic field induced evolution from bulk exciton to 2DEG-free hole luminescence in modulation doped heterojunctions, PHYSICA E, 12 (1-4): 524-527 (2002).

  28. W. Breuer, D. Weiss, V. Umansky, Commensurability effects in two-dimensional electron gases with periodically arranged Ni and NiFe nanopillars, PHYSICA E, 12 (1-4): 216-219 (2002).

  29. C. Mitzkus, W. Kangler, D. Weiss, W. Wegscheider, V. Umansky, Anomalous temperature dependence of commensurability oscillations in one- and two-dimensional lateral superlattices, PHYSICA E, 12 (1-4): 208-211 (2002).

  30. S.I. Dorozhkin, J.H. Smet, K. von Klitzing, V. Umansky, W. Wegscheider, R.J. Haug, K. Ploog, Measurements of the compressibility of the composite fermion metallic state in a 2D electron system. PHYSICA E, 12 (1-4): 97-100 (2002).

  31. M. Tornow, M. Heiblum, D. Mahalu, H. Shtrikman, V. Umansky, A novel split gate design to study interaction effects in quantum wires, PHYSICA E 13 (1), 89-93 (2002).

  32. B.M. Ashkinadze, V. Voznyy, E. Cohen, A. Ron, V. Umansky, Condensation of bulk excitons on a magnetized two-dimensional electron gas in modulation-doped heterojunctions Phys. Rev B 65, 073311 (2002).

  33. H.A. Nickel, T.M. Yeo, A.B. Dzyubenko, B.D. McCombe, A. Petrou, A.Y. Sivachenko, W. Schaff, V. Umansky, Internal transitions of negatively charged magnetoexcitons and many body effects in a two-dimensional electron gas. Phys.Rev.Lett. 88 (5): art. no. 056801 FEB 4 (2002).

  34. L.V. Kulik, I.V. Kukushkin, V.E. Kirpichev, J.H. Smet, K. von Klitzing, V. Umansky, W. Wegscheider, Cyclotron spin-wave in the 2D electron system. JETP Lett. 74 (5): 270-273 (2001).

  35. Y. Yayon, M. Rappaport, V. Umansky, I. Bar-Joseph, Excitonic emission in the presence of a two-dimensional electron gas: A microscopic view. Phys. Rev. B 64 (8),AUG 15 (2001).

  36. C. Albrecht, J.H. Smet, K. von Klitzing, D. Weiss, V. Umansky, H. Schweizer, Evidence of Hofstadter's fractal energy spectrum in the quantized Hall conductance. Phys. Rev. Lett. 86, 147-150 (2001).

  37. D. Mandelik, M. Schniederman, V. Umansky, I. Bar-Joseph, Monolithic integration of a quantum-well infrared photodetector array with a read-out circuit, Appl. Phys. Lett. 78 (4), 472-474, (2001).

  38. S.I. Dorozhkin, J.H. Smet, K. von Klitzing, V. Umansky, R.J. Haug, K. Ploog, Comparison between the compressibilities of the zero field and composite-fermion metallic states of the two-dimensional electron system. Phys. Rev. B 63,1301 (2001).

  39. B.M. Ashkinadze, E. Linder, V. Umansky, Dimensional magnetoplasma resonance detected by free-exciton photoluminescence in modulation-doped GaAs/AlxGa1-xAs heterojunctions, Phys. Rev. B 62, 10310-10317 (2000).

  40. T.G. Griffiths, E. Comforti, M. Heiblum, A. Stern, V. Umansky , Evolution of quasiparticle charge in the fractional quantum hall regime, Phys. Rev. Lett., 85, 3918-3921 (2000).

  41. S. Jobst, S. Zwerschke, J.H. Smet, R.R. Gerhardts, D. Weiss, K. von Klitzing K, V. Umansky, Composite fermions in a weakly density modulated 2DEG: direct evidence of a periodic magnetic field around nu=1/2, PHYSICA E, 6, 87-90 (2000).

  42. C. Albrecht, J. H. Smet, D. Weiss, K. von Klitzing, R. Hennig, M. Langenbuch, M. Suhrke, U. Rössler, V. Umansky, H. Schweizer, Femiology of two dimensional lateral superlattices, Phys. Rev. Lett., 83, 2234-2237 (1999).

  43. J.H. Smet, S. Jobst, K. von Klitzing, D. Weiss, W. Wegscheider, V. Umansky, Commensurate composite fermions in weak periodic electrostatic potentials: direct evidence of a periodic effective magnetic field, Phys. Rev. Lett. 83, 2620-2623 (1999).

  44. M. Reznikov R. De-Picciotto, Griffiths TG, M. Heiblum, V. Umansky, Observation of quasiparticles with one-fifth of an electron's charge, NATURE 399, 238-241 (1999).

  45. V. Ciulin , G. Finkelstein, S. Haacke, J.D. Ganiere, V. Umansky, I. Bar-Joseph, B. Deveaud, Dynamics of charged excitons in GaAs quantum wells under high magnetic field, PHYSICA B, 258, 466-469, (1998).

  46. G. Finkelstein, V. Umansky, I. Bar-Joseph, V. Ciulin, S. Haacke, J.D. Ganiere, B. Deveaud, Charged exciton dynamics in GaAs quantum wells, Phys. Rev. B 58, 12637-12640 (1998).

  47. R. De-Picciotto, M. Reznikov, M. Heiblum, V. Umansky, G. Bunin, D. Mahalu, Direct Observation of a Fractional Charge, PHYSICA E, 3, 47-51 (1998).

  48. C. Albrecht, J.H. Smet, D. Weiss, K. Von Klitzing, V. Umansky, H. Schweizer, Novel Magnetoresistance Oscillations in Short-Period Lateral Superlattices, PHYSICA B, 251, 914-917 (1998).

  49. N.Q. Balaban, U. Meirav, Hadas Shtrikman and V. Umansky, High-Frequency Edge Excitations in the Quantum Hall Regime. PHYSICA B, 251, 435-439 (1998).

  50. R. De-Picciotto, M. Reznikov, M. Heiblum, V. Umansky, G. Bunin, D. Mahalu. Direct Observation of a Fractional Charge, PHYSICA B, 251, 395-400 (1998).

  51. E. Buks, R. Schuster, M. Heiblum, D. Mahalu, V. Umansky. Dephasing Due to Which Path Detector. PHYSICA B, 251, 295-301 (1998).

  52. E. Buks, R. Schuster, M. Heiblum, D. Mahalu, V. Umansky. Dephasing in Electron Interference by a Which-Path Detector . NATURE, 391, 871-874 (1998).

  53. K.Gartsman, D. Cahen, A. Kadyshevitch, J. Libman, T. Moav, R. Naaman, A. Shanzer, V. Umansky, A. Vilan. Molecular Control of a GaAs Transistor. Chemical Physics Letters, 283, 301-306 (1998).

  54. Umansky, G. Bunin, K. Gartsman, C. Sharman, R. Almuhannad, M. Heiblum, I. Bar-Joseph and U. Meirav. All GaAs/AlGaAs readout circuit for Quantum Well Infrared Detector Focal Plane Array. IEEE Transactions on Electron Devices, 44, 1807-1813 (1997).

  55. R. De-Picciotto, M. Reznikov, M. Heiblum, V. Umansky, G. Bunin, D. Mahalu, Direct Observation of a Fractional Charge, NATURE 389, 162-164 (1997).

  56. V. Umansky, R. De-Piccioto and M. Heiblum. Extremely High Mobility Two Dimensional Electron Gas: Evaluation of Scattering Mechanisms. Appl. Phys. Lett., 71, 5, 683-685 (1997).

  57. N.Q. Balaban, U. Meirav, Hadas Shtrikman and V. Umansky. Observation of the logarithmic dispersion of high frequency edge excitations. Phys. Rev. B 55, 20, 13397-13400 (1997).

  58. R. Shikler, M. Heiblum, V. Umansky. Spatial Correlation of Ionized Donors and Its Effect on Scattering Time and Spin Splitting in a 2-Dimensional Electron-Gas, Phys. Rev. B 55, 23, 15427-15430 (1997).

  59. R. Schuster, E. Buks, M. Heiblum, D. Mahalu, V. Umansky and Hadas Shtrikman. Phase Measurement in a Quantum dot via a double-slit interference experiment,NATURE, 385, 417 (1997).

  60. E. Buks, R. Schuster, M. Heiblum, D. Mahalu, V. Umansky and H. Shtrikman. Measurement of Phase and Magnitude of the Reflection Coefficient of a Quantum Dot, Phys. Rev. Lett. 77, 4664 (1996).

  61. Messica, A. Soibel, U. Meirav, Ady Stern, Hadas Shtrikman, V.Umansky and D. Mahalu. Suppression of Conductance in Surface Superlattice by Temperature and Electric Field. Phys. Rev. Lett. 78, 705 (1997).

  62. Messica, U. Meirav, Hadas Shtrikman, V. Umansky and D. Mahalu, Bistability and dynamic depopulation in transport through a system of weakly coupled quantum wires. Phys. Rev. B 54, R5247 (1996).

  63. Yacoby, M. Heiblum, V. Umansky, H. Shtrikman and D. Mahalu, Unexpected Periodicity in an Electronic Double Slit Interference Experiment., Phys. Rev. Lett. 73, 3149-3152 (1994).

  64. A.Yacoby, M. Heiblum, H. Shtrikman, V. Umansky and D. Mahalu, Dephasing of ballistic electrons as function of temperature and carrier density, Semicond. Sci. Technol. 9, 907-910 (1994).

  65. B. Houli, V. Umansky and M. Heiblum., Low-energy electron beam lithography with 30 nm resolution, Semicond. Sci. Technol. 8, 1490-1492 (1993).