HKUEMS :: Event Details

Quantum Capacitance Anomalies of Two-Dimensional Non-Equilibrium States Under Microwave Irradiation
posted by Department of Physics for HKU and Public
Event Type: Public Lecture/Forum/Seminar/Workshop/Conference/Symposium
Event Nature: Science & Technology

Event Details


Quantum Capacitance Anomalies of Two-Dimensional Non-Equilibrium States Under Microwave Irradiation

Dr. Chi Zhang
(ICQM, Peking University)


The microwave-induced resistance oscillations (MIRO) [1, 2] and the related zero-resistance states (ZRS) [3, 4] are novel phenomena in ultraclean two-dimensional electron system (2DES). In fact, there are still important puzzles in this research area.

We report our direct study of the compressibility on ultrahigh mobility two-dimensional electron system (μ ∼ 1 × 107 cm2/V sec) in GaAs/AlGaAs quantum wells under microwave (MW) irradiation. The field penetration current results show that the quantum capacitance oscillates with microwave induced resistance oscillations (MIRO), however, the trend is opposite with respect to the compressibility for usual equilibrium states in previous theoretical explanations. The anomalous phenomena provide a platform for study on the non-equilibrium system under microwave, and point to the current domains [5] and inhomogeneity induced by radiation. Moreover, the quantum capacitance indication for multi-photon process around j = 1/2 is detected under intensive microwave below 30 GHz.

[1] M. A. Zudov, R. R. Du, J. A. Simmons, and J. L. Reno, Phys. Rev. B 64, 201311(R) (2001).
[2] P. D. Ye, L. W. Engel, D. C. Tsui, J. A. Simmons, J. R. Wendt, G. A. Vawter, and J. L. Reno, Appl. Phys. Lett. 79, 2193 (2001).
[3] R. G. Mani, Jurgen H. Smet, Klaus von Klitzing, Venkatesh Narayanamurti, William B. Johnson, and Vladimir Umansky, Nature 420, 646 (2002).
[4] M. A. Zudov, R. R. Du, L. N. Pfeiffer, and K. W. West, Phys. Rev. Lett. 90, 046807 (2003).
[5] A. V. Andreev, I. L. Aleiner, and A. J. Millis, Phys. Rev. Lett. 91, 056803 (2003).

Coffee and tea will be served 20 minutes prior to the seminar.
Anyone interested is welcome to attend.

Date/Time23/05/2017 16:00-17:00
VenueRm 522, 5/F, Chong Yuet Ming Physics Building, HKU

Registration Instruction

Registration is not required.

Contact Information

Should you have any enquiries, please feel free to contact Ms Eva Wong by email at or by phone at 2859 2360 or by fax at 2559 9152.