Dr. Zhao's Research Group

Members

Research

Equipment

Publications

Talks

Teaching

News

Links

Contact

Zhao

Guo-meng (Peter) Zhao
Professor

California State University, Los Angeles
Ph.D. 1997, University of Zurich
Office: ASCB 121 C
Telephone: (323) 343-2139    
Specialization: Experimental condensed matter physics
(see CV)                                                                                   

Education

 

10/95-07/97    Ph.D. in Physics, Physics Department, University of Zurich with K. A. Muller (Nobel Laureate, 1987)

09/88-12/90    M. A. in Physics, Physics Department, University of Southern California

09/85-07/88    Ph. D. Candidate, Physics Institute, Chinese Academy of Sciences

09/81-07/85    B. S. in Physics, Zhejiang University, Hangzhou, China

 

Professional Experience

 

9/13-               Full Professor, Department of Physics and Astronomy, California State University, Los Angeles

9/08-8/13        Associate Professor, Department of Physics and Astronomy, California State University, Los Angeles                 

9/02-8/08        Assistant Professor, Department of Physics and Astronomy, California State University, Los Angeles

5/01-8/02        Research Associate Professor, Physics Department/TcSUH, University of Houston

7/97-5/01        Faculty Research Associate, Physics Department, University of Zurich

12/97-6/98      Research Associate, Center for Superconductivity Research, Physics Department,

                        University of Maryland

 

Scholarly Highlights

  • 101 published papers in highly reputable journals or books (including 2 in Nature, 1 in Nano Letters, 7 in Physical Review Letters, 37 in Physical Review B, and 9 as book chapters)
  • Over 2500 citations including over 600 citations to the 96 Nature paper
  • First observations of the giant oxygen-isotope effects on the Curie-temperature, charge-ordering temperature, and electrical transport properties in doped manganites. These discoveries provide direct evidence for strong electron-phonon interactions and the existence of polarons/bipolarons in doped manganites.
  • First observations of various unconventional oxygen-isotope effects in cuprates including the oxygen-isotope effects on the effective supercarrier mass, on the antiferromagnetic exchange energy, and on the charge-stripe formation temperature. In particular, the observation of the oxygen-isotope effect on the effective supercarrier mass directly demonstrates the polaronic nature of supercarriers, which is crucial to the understanding of the microscopic mechanism of high-temperature superconductivity.
  • Identification of the intrinsic pairing gap symmetry in the optimally and overdoped cuprate superconductors (BCS-like superconductors), which is extended s-wave (s+g wave) with eight line nodes in hole-doped cuprates, and nodeless s-wave in electron-doped cuprates. This appears to be in contrast to the d-wave superconducting gap symmetry inferred from some surface and phase-sensitive experiments that probe the superconducting state in intrinsically underdoped surfaces/interfaces.
  • Proof for intersite bipolaronic superconductivity in underdoped cuprates where the superconducting gap symmetry of the Bose-Einstein condensate is d-wave, in agreement with the phase-sensitive experiments and angle-resolved photoemission experiments. The d-wave superconducting gap symmetry is not associated with the pairing gap symmetry and pairing interaction, but with the anomalous kinetic process of the intersite bipolarons. 
  • Identification of bosonic modes mediating electron pairing for high-temperature superconductors, showing evidence for predominantly phonon-mediated pairing mechanism and ruling out magnetic pairing mechanism.
  • Uncovering the secret of high-temperature superconductivity in cuprates, bismuthates, pnictides, MgB2, and doped C60.  The lattice polaronic effect with a mass enhancement factor of 1.5-6.0, commonly observed in these superconductors is the key to high-temperature superconductivity.
  • Providing evidence for phase-incoherent ultrahigh temperature superconductivity in carbon nanotubes
  • First observation of giant magnetic moment enhancement of magnetic nanoparticles embedded in multiwalled carbon nanotubes
  • First observation of anomalous thermal hysteresis of the high-field magnetic moment of magnetic nanoparticles embedded in multiwalled carbon nanotubes: Consistent with the high-field paramagnetic Meissner effect due to ultrahigh temperature superconductivity in carbon nanotubes
  • First observation of finite-size scaling relations in several magnetic nanoparticle systems: Quantitative agreement with theory
  • First identification of the intrinsic correlation length exponent in nickel: Resolving a long-standing controversy in the field

 

Professional Activities

  • Invited speaker in 14 international conferences including an invited speaker in the American Physical Society March Meeting
  • Invited speaker in 27 colloquia/seminars in the academic and research institutions including the Stanford University, the Brown University, USC, and UCLA
  • Session Chair in 1999 APS (American Physical Society) March Meeting
  • Session Chair in the 32nd Condensed Matter Theory Workshop, 2008
  • Editorial Advisory Board Member to Open Condensed Matter Physics Journal, Open Condensed Matter Physics Reviews, and Open Condensed Matter Physics Letters
  • Referee for Physical Review B, Physical Review Letters, Journal of Applied Physics, Applied Physics Letters, Physics Letters A, and for over 10 other important physics journals

Honors and Awards

  • Recipient of the most outstanding Ph.D. dissertation award, University of Zurich, Switzerland, 1997
  • Recipient of the most outstanding undergraduate student award, Zhejiang University, China, 1983
  • Cottrell college science award from Research Corporation (2004 and 2005)

 

Research Interests

 

My research interests include studying novel materials exhibiting extraordinary superconducting, magnetoresistive, ferroelectric, optical, and magnetic properties. These novel materials include high-temperature superconducting cuprates, colossal magnetoresistive manganites, ferroelectric and photorefractive barium titanates, and quasi-one-dimensional carbon nanotubes. I am particularly interested in unconventional oxygen-isotope effects on electrical, magnetic, and thermal properties of the provskite oxides to clarify the roles of electron-phonon interactions in the microscopic origins of high-temperature superconductivity in cuprates, the colossal magneteoresistance in manganites, and the unusual photorefractive effect in barium titanates. I am also interested in theoretical studies of the pairing interactions and gap symmetry in cuprates to provide essential constraints on the microscopic theory of high-temperature superconductivity. My current experimental research focuses on magnetic and superconducting nanostructures, magnetic nanoparticles embedded in multi-walled carbon nanotubes.