# Sergey Vitkalov

# Sergey Vitkalov

## Professor National Science Foundation Career Grantee

**School/Division**

- Division of Science

**Department**

- Physics

**Office**

2012-present Professor, Physics Department CCNY

2006-2012 Associate Professor, Physics Department, CCNY

2002-2006 Assistant Professor, Physics Department, CCNY

1998-2002 Research Professor, Research Foundation, CUNY

1997-1998 Research Associate, Chemistry Department, University of Florida

1989-1999 Senior Research Associate, P.N.Lebedev Physical Institute of Russian

Academy of Sciences, Russia

1986-1989 Research Associate, P.N.Lebedev Physical Institute of Russian

Academy of Sciences, Russia

1986 - Ph.D. at Institute of Solid State Physics of Russian Academy of Science.

Thesis: "Nonlinear microwave effects in Bismuth at high magnetic field"

Thesis advisers: V. F. Gantmakher and G. I. Leviev

1981 - Master Degree at Moscow Institute of Physics and Technology

Physics 554

2003 Spring: Science 10101 (Honors Center)

2003 Fall: Science and Technology in NYC (Honors College)

Photos: NAC building CCNY: #1, #2, #3, #4, #5, #6

Final Conference Fall2003; Graduate Center #1, #2, #3, #4, #5, #6, #7, #8

2004 Spring: Introductory Physics 207

2004 Fall: Introductory Physics 207 (Section MM2)

Photos: roomJ3 J417 J417 #2

2004 Fall: Science and Technology in NYC (Honors College)

Honors College Conference; December 2004 #1, #2, #3, #4, #5, #6, #7, #8

2005 Fall: Science and Technology in New York City (Honors College)

Photos: P1, P2, P3, P4, P5, P6

2005 Fall: Introductory Physics 207 (Section GH)

Photos: P1, P2, P3, P4, P5

2006 Fall: Introductory Physics 207 (Section GH)

Photos: P1, P2

2007 Spring: Introductory Physics 204

Photos: P1 P2 P3

2007 Fall: Introductory Physics 207 (Section GH-GH2)

Photos: P1, P2

2008 Spring: Introductory Physics 208 (Section ST-ST2)

Photos: P1, P2

2009 Fall: Introductory Physics 207 (Section GH-GH4)

Photos: P1, P2, P3

2010 Spring: Science 10101 (Honors Program)

Presentations: Charging Hair, Physics of Dance (PD), PD2, PD3, PD4

Final Exam: P1, P2, P3, P4, P5, P6

Group Photos: P1, P2, P3

2010 Fall: Introductory Physics 207 ( Sections GH-GH4)

Photos: P1, P2, P3, P4

2011 Fall: Introductory Physics 207 ( Sections GH-GH5)

Photos: P1, P2, P3

2012 Fall:

Physics 207

Physics 554

Research is focused on dynamical and nonlinear properties of low dimensional

electron systems. Goals are to understand fundamental properties of electron

transport in nano-scaled objects.

RESEARCH

Nonlinear Properties of 2D electrons in crossed electric and magnetic field.

Two dimensional highly mobile electrons, placed in a quantizing magnetic field, demonstrate strong, several-fold reduction of resistance in response to dc electric field E. The nonlinearity is caused by a nontrivial, energy dependent heating, which occurs in systems with the quantized (discrete) spectrum. Our recent experiment indicates, that the dc driven heating occurs with no increase of a temperature or global broadening of the electron distribution. Instead there is strong overheating and overcooling of 2D electrons, which in the energy space occurs "locally", providing a stratification of the dc driven phase flow and leading the electron system into a state with a zero differential resistance. The peculiar heating results in an exceptionally strong violation of Ohm's Law, which is unusual for degenerate electrons. In addition, our results indicate that, in general, the effective overheating in the systems with discrete spectrum is significantly stronger than the one in systems with a continuous and homogeneous distribution of the energy levels.

Nonlinear response of low dimensional systems

Quantum dots:

Nonlinear directed transport in mesoscopic objects is a subject of considerable fundamental interest due to potential applications in nanoelectronics. An unavoidable break of the spatial inversion symmetry by impurity potential leads to photovoltaic effects in small quantum systems. More recently, various competing mechanisms of the photovoltaic effects and rectification in quantum dots have been proposed and investigated experimentally. Most efforts have been focused on the nonlinear properties of mesoscopic objects in the regime, where the electron transport is controlled by quantum interference. In our recent research we have studied the nonlinear electron transport in a different regime, where the classical ballistic trajectories appear to provide the dominant contribution to the nonlinearity. In magnetic fields we have observed a gigantic reduction of the directed electron transport through ballistic dot with lateral size, d = 1 micron, significantly smaller than the mean free path (8 micron) of the electrons in adjoining 2D layers.

Micro-thermocouple:

We have reported measurements of the rectification of microwave radiation (0.7–20 GHz) at the boundary between two-dimensional electron systems, created by a narrow gap split gate on a silicon surface. We have studied the system of two metals; for different temperatures, electron densities, and microwave power. We have found that this tiny system of two different 2D metals work as a controllable micro-thermocouple. Microwaves heat the boundary between two dissimilar 2D metals, inducing a thermoelectric voltage. A comprehensive theory, calculating the voltage, is proposed. Excellent quantitative agreement is obtained between theory and experiment.

Scott Dietrich, Sergey Vitkalov, D. V. Dmitriev and A. A. Bykov Quantum lifetime of 2D electron in magnetic field, Physical Review B, 85, 115312 (2012).

CCNY Authors assigned: Scott Dietrich, Sergey Vitkalov

Scott Dietrich, Sean Byrnes, Sergey Vitkalov, D. V. Dmitriev and A. A. Bykov Quantum oscillations in crossed electric and magnetic fields, Physical Review B, 85, 155307 (2012).

CCNY Authors assigned: Scott Dietrich, Sean Byrnes, Sergey Vitkalov

D. V. Dmitriev, I. S. Strigin, A. A. Bykov, S. Dietrich, S. A. Vitkalov Transport scattering time and quantum lifetime of 2D electrons in GaAs/ AlAs heterojunctions, JETP Letters, 95, 467 (2012).

CCNY Authors assigned: S. Dietrich, S. A. Vitkalov

Bykov A. A., Goran A. V., Vitkalov S. A. Interference of magneto-intersubband and phonon-induced resistance oscillations in single GaAs quantum wells with two populated subbands, Physical Review B, 81, 155322 (2010).

CCNY Authors assigned: Vitkalov S. A.

Vitkalov S. A. Nonlinear Transport of 2D Electrons in Crossed Electric and Quantizing Magnetic Fields, Invited Talk,Bulletin of the American Physical Society, Volume 55, Number 2,http://meetings.aps.org/link/BAPS.2010.MAR.J2.3. (2010).

CCNY Authors assigned: Vitkalov S. A.

Vitkalov S. A., Goran A. V., Bykov A. A., Toropov A. I. Effect of electron-electron scattering on magneto-intersubband resistance oscillations of two dimensional electrons in GaAs quantum well, Bulletin of the American Physical Society, http://meetings.aps.org/link/BAPS.2010.MAR.T25.6 (2010).

CCNY Authors assigned: Vitkalov S. A.

A. A. Bykov, E. G. Mozulev, S. A. Vitkalov Zero differential resistance in a double quantum well at high filling factors, Jetp Letters, 92, p.475 (2010).

CCNY Authors assigned: S. A. Vitkalov

A. V. Goran, A. A. Bykov, A. I. Toropov and S. A. Vitkalov Coexistence of two types of microwave induced resistance oscillations in 2D electron gas at large filling factors, Proceedings of 18th International Symposium: Nanostuctures; Physics and Technology", St. Petersburg Russia, p.73 (2010).

CCNY Authors assigned: S. A. Vitkalov

S. A. Vitkalov and A. A. Bykov Quantal heating in strong magnetic fields, Proceedings of 18th International Symposium: Nanostuctures; Physics and Technology", St. Petersburg Russia, 55 (2010).

CCNY Authors assigned: S. A. Vitkalov

Zhang Jing Qiao, Vitkalov Sergey, Bykov A. A. Nonlinear resistance of two-dimensional electrons in crossed electric and magnetic fields, Physical Review B, 80, 045310 (2009).

CCNY Authors assigned: Vitkalov S. A. , Zhang Jing Qiao

Vitkalov S. A., Romero N., Bykov A. A. Warming in systems with discrete spectrum: spectral diffusion of two dimensional electrons in magnetic field, Bulletin of the American Physical Society, Volume 54, Number 1 (2009).

CCNY Authors assigned: Vitkalov S. A., Natalia Romero

Vitkalov Sergey Microwave rectification at a boundary between two two-dimensional electron systems., Invited talk, State University of New York, Buffalo (2009).

CCNY Authors assigned: Vitkalov Sergey

Vitkalov S. A. Spectral diffusion of two-dimensional electrons in crossed electric and quantized magnetic fields., Invited talk, National Research Council of Canada, Institute for Microstructu (2009).

CCNY Authors assigned: Vitkalov Sergey

Vitkalov Sergey Warming in systems with discrete spectrum, Invited talk, Symposium on Spin Physics and Nano-Magnetism, CUNY 2009 (2009).

CCNY Authors assigned: Vitkalov Sergey

Goran A. V., Bykov A. A., Toropov A. I., Vitkalov S. A. Effect of electron-electron scattering on magnetointersubband resistance oscillations of two-dimensional electrons in GaAs quantum wells, Physical Review B, 80, 193305 (2009).

CCNY Authors assigned: Vitkalov S. A.

Vitkalov S. A., Zhang Jin Qiao, Romero N., Bykov A. A. Nonlinear resistance of two-dimensional electrons in crossed electric and quantized magnetic fields, Condensed Matter Seminar, The City College of New York, Physics Department (2009).

CCNY Authors assigned: Vitkalov S. A., Zhang Jin Qiao, Romero N.,

Vitkalov S. A. Nonlinear transport of 2D electrons in crossed electric and quantizing magnetic fields ( Review Article), International Journal of Modern Physics B, 23, 4727 (2009).

CCNY Authors assigned: Vitkalov S. A.

Natalia Romero , Sean McHugh , Myriam P. Sarachik , Sergey A. Vitkalov , A. A. Bykov Effect of parallel magnetic field on the zero-differential resistance state, Bull. Am. Phys. Soc., http://meetings.aps.org/link/BAPS.2009.MAR.A31.5 (2009).

CCNY Authors assigned: Myriam P. Sarachik , Sergey A. Vitkalov

Jing Qiao Zhang, Sergey Vitkalov, A. A. Bykov, and A. I. Toropov Nonlinear transport of 2D electrons in magnetic fields, International Journal of Modern Physics B, v. 23, p.2689 (2009).

CCNY Authors assigned: Jing Qiao Zhang, Sergey Vitkalov

A. V. Goran, A. A. Bykov, A. I. Toropov and S. A. Vitkalov Effect of electron-electron scattering on magneto-intersubband resistance oscillations of two dimensional electrons in GaAs quantum well, Physical Review B, 80, p.193305 (2009).

CCNY Authors assigned: S. A. Vitkalov

N. Romero, S. McHugh, M. P. Sarachik, S. A. Vitkalov, and A. A. Bykov Effect of parallel magnetic field on the zero-differential resistance state, Physical Review B, 78, p. 153311 (2008).

CCNY Authors assigned: N. Romero, S. McHugh, M. P. Sarachik, S. A. Vitkalov

N. Romero Kalmanovitz, A. A. Bykov, Sergey Vitkalov, and A. I. Toropov Warming in systems with a discrete spectrum: Spectral diffusion of two-dimensional electrons in a magnetic field, Physical Review B, 78, p. 085306 (2008).

CCNY Authors assigned: N. Romero Kalmanovitz, Sergey Vitkalov

N. Romero Kalmanovitz, I. Hoxha, Y. Jin, S. A. Vitkalov, M. P. Sarachik, Ivan A. Larkin, and T. M. Klapwijk Scaling of thermoelectric voltage induced by microwave radiation at the boundary between two-dimensional electron systems, Physical Review B, 77, p.035415 (2008).

CCNY Authors assigned: N. Romero Kalmanovitz, I. Hoxha, Y. Jin, S. A. Vitkalov, M. P. Sarachik

N. Romero Kalmanovitz I. Hoxha Y. Jin S.A. Vitkalov M.P. Sarachik, I.A. Larkin, T.M. Klapwijk Scaling of thermoelectric voltage induced by microwave radiation at the boundary between two-dimensional electron systems, Bulletin of American Physical Society, v. 53, N2, U37.00013 (2008).

CCNY Authors assigned: N. Romero Kalmanovitz I. Hoxha Y. Jin S.A. Vitkalov M.P. Sarachik

Sergey Vitkalov Jing-Qiao Zhang, A. A. Bykov, A. K. Kalagin, A. K. Bakarov Zero differential resistance state in 2D dimensional electron system in strong magnetic field., Bulletin of American Physical Society, V53, N2, U37.00005 (2008).

CCNY Authors assigned: Sergey Vitkalov Jing-Qiao Zhang

Sergey Vitkalov, Jing-Qiao Zhang, Z. D. Kvon Directed electron transport through ballistic dot under microwave radiation, 29th International conference on the Physics of Semiconductors, Rio de Janeiro, Brazil (2008).

CCNY Authors assigned: Sergey Vitkalov, Jing-Qiao Zhang,

SERGEY VITKALOV, JING QIAO ZHANG, A. A. BYKOV, A. I. TOROPOV Nonlinear transport of 2d electrons in magnetic field, 18th International Conference on High Magnetic Field, San-Paulo, Brazil (2008).

CCNY Authors assigned: SERGEY VITKALOV, JING QIAO ZHANG

Romero N., McHugh S., Sarachik M. P., Vitkalov S. A. and Bykov A. A. Effect of parallel magnetic field on the zero-differential resistance state, March meeting of the American Physical Society, http://meetings.aps.org/link/BAPS.2008.MAR.A21.7 (2008)., A21.7. (2008).

CCNY Authors assigned: Sarachik M. P., Vitkalov S. A.

Kalmanovitz N. R., Hoxha I., Jin Y., Vitkalov S. A., Sarachik M. P., Larkin A. I. and Klapwijk T. M. Scaling of thermoelectric voltage induced by microwave radiation at the boundary between two-dimensional electron systems, Physical Review B, 77, 035415 (2008).

CCNY Authors assigned: Vitkalov S. A., Sarachik M. P.

Romero N., McHugh S., Sarachik M. P., Vitkalov S. A., and Bykov A. A. Effect of parallel magnetic field on the zero-differential resistance state, Physical Review B, 78, 153311 (2008).

CCNY Authors assigned: Sarachik M. P., Vitkalov S. A.

Bykov A. A., Zhang Jing-qiao, Vitkalov Sergey, Kalagin A. K., Bakarov A. K. Zero-Differential Resistance State of Two-Dimensional Electron Systems in Strong Magnetic Fields, Physical Review Letters, 99, 116801 (2007).

CCNY Authors assigned: Vitkalov S. A.

Vitkalov Sergey Nonlinear resistive state of 2D electrons in magnetic fields, Invited talk, Condensed Matter Seminar, Brookhaven National Laboratory , December 2007 (2007).

CCNY Authors assigned: Vitkalov S. A.

Larkin A., Vitkalov S. A., Sarachik M. P. Rectification of Microwave Radiation at a Split Gate on a Silicon MOSFET, Brazilian Journal of Physics, (2007).

CCNY Authors assigned: Sarachik,Vitkalov

Zhang J.S., Bykov A. A., Kalagin A. K., Bakarov A. K. Effect of a dc electric field on the longitudinal resistance of two-dimensional electrons in a magnetic field, Phys. Rev. B, Rapid Communications, 75, 081305 (2007).

CCNY Authors assigned: Zhang, Vitkalov

Bykov A. A., Marchishin I. V., Bakarov A. K., Zhang J., Vitkalov S. Hall Breakdown in Modulated Doped GaAs/AlAs heterostructure, JETP Letters, 85, 69 (2007).

CCNY Authors assigned: Zhang,Vitkalov

Zhang Jing-qiao, Vitkalov Sergey, Kvon Z. D., Portal J. C., Wieck A. Directed Electron Transport through a Ballistic Quantum Dot under Microwave Radiation, Physical Review Letters, 97, 226807 (2006).

CCNY Authors assigned: Vitkalov S. A.

A. A. Bykov, Jing-qiao Zhang, Sergey Vitkalov, A. K. Kalagin, and A. K. Bakarov Effect of dc and ac excitations on the longitudinal resistance of a two-dimensional electron gas in highly doped GaAs quantum wells, Physical Review B, 72, 245307 (2005).

CCNY Authors assigned: Vitkalov