John Y.T. Wei 
Associate Professor
     Condensed Matter Physics


60 St. George Street,  Toronto, ON  M5S1A7  Canada
Phone:  (416) 946-5943    Fax:  (416) 978-2537
Office:  MP 081                E-mail:  wei at


Scholar, Canadian Institute for Advanced Research (since 1999) 

Member, Centre for Quantum Information and Quantum Control (since 2004) 
Member, Brockhouse Institute for Materials Research (since 2003) 
Postdoctoral Scholar & Research Fellow, California Institute of Technology (1996-99) 
Joint Research Student, IBM T. J. Watson Research Center (1992-95)
M.S. & Ph.D., Columbia University (1991 & 1996) 
B.A., University of California Berkeley (1987)

Research        Go to Research Page

Interests: Nanoscale studies of exotic superconductivity, extreme magnetism & topological phenomena in oxides & intermetallics.
Materials: Transition-metal oxides/chalcogenides, Fe-chalcogenides/pnictides, CeCoIn5, Skutterudites, heavy-metal chalcogenides.
: C
ryomagnetic scanning tunneling microscopy (STM) & point-contact spectroscopy (PCS), pulsed laser deposition (PLD).

My research is devoted to nanoscale study of unconventional superconducting and magnetic materials, as well as the emerging new class of topological materials.  It is intended to examine the electronic properties of these materials at very short length scales, where the quantum ordering effects occur coherently without being averaged out over macroscopic distances, and manifest themselves as novel phenomena.  It involves an unique combination of cryomagnetic, nanoprobe and nanofabrication techniques, with the application of both “top-down” and “bottom-up” approaches.  Detailed understanding of these exotic electronic materials is of fundamental importance to condensed matter physics, and could also lend them to novel technological applications, ranging from superconducting to spintronic devices, as well as elements for quantum computation.  

  CFI_logo   OIT_logo  OCE_logo ciar_logoCentre for Quantum Information and Quantum
                    Control (CQIQC)  BIMR   

Courses Taught

Physics 294H:        Thermal Physics for Engineering Sciences
Physics 335H:        Quantum Mechanics for Electrical & Computer Engineering
Physics 1850F:       Foundations of Condensed Matter Physics 
Physics 326/327:    3rd/4th-Year Undergraduate Laboratory 
Physics 225H:        2nd-Year Undergraduate Laboratory 
Physics 281S:        Introduction to Quantum Physics

Select Publications

1. Lateral Imaging of the Superconducting Vortex Lattice using Doppler Modulated Scanning Tunneling Microscopy
Applied Physics Letters 99, 192505 (2011). 

Andreev Nanoprobe of Half-Metallic CrO2 Films using Superonducting Cuprate Tips
Applied Physics Letters
99, 192508 (2011).  pdf

3. Scanning tunneling spectroscopy study of c-axis proximity effect in epitaxial bilayer manganite/cuprate thin films,
Physical Review B 84 104522 (2011). 

Spectroscopic signatures of the Larkin-Ovchinnikov state in the conductance characteristics of a normal-metal/superconductor junction
Physical Review B
85 014503 (2012). pdf

STM Spectroscopy on Superconducting FeSe1−xTex Single Crystals at 300 mK
Journal of Physics and Chemistry of Solids, Volume 72-5, 483 (2011). pdf

6. Local tunneling probe of (110) Y0.95Ca0.05Ba2Cu3O7-d thin films in a magnetic field
Physical Review B 82, 054505 (2010).  pdf

7. Andreev Spectroscopy Study of Multigap Pairing in PrOs4Sb12
Journal of the Physical Society of Japan 77, 21 (2008).  pdf

8. Tunneling Spectroscopy on c-axis Y1-xCaxBa2Cu3O 7-d Thin Films
Physical Review Letters 98, 177003 (2007). 

9. Conductance characteristics between a normal metal and a 2D Fulde-Ferrell-Larkin-Ovchnnikov superconductor:
the Fulde-Ferrell state
Physical Review B 73, 214514 (2006). pdf

10. Suppression of low-energy Andreev states by a supercurrent in YBa2Cu3O7-d,
Physical Review B 72, 054513 (2005).

11. Spectroscopic Evidence for Multiple Order Parameter Components in the Heavy Fermion Superconductor CeCoIn5,
Physical Review Letters 94, 107005 (2005). pdf

Selective epitaxial growth of sub-micron complex oxide structures by amorphous SrTiO3,
Applied Physics Letters 86, 192509 (2005)
. pdf

Nuclear Spin Relaxation of  8Li in a Thin Film of La_0.67Ca_0.33MnO_3
R. I. Miller et al., preprint, to appear in Physica B (2006).

Evidence for Current-Driven Phase Slips in YBa_2Cu_3O_7-d Microstrips
P. Morales, M. DiCiano, and  J. Y. T. Wei, preprint, to appear in AIP Conf. Proc. for LT24 (2006).

Point Contact Spectroscopy Study of the Ferromagnetic Superconductor ZrZn_2
C. Turel, M. Tanatar, R. Hill, E. Yelland, S. Hayden, J. Y. T. Wei, preprint, to appear in AIP Conf. Proc. for LT24 (2006).

Selective epitaxial growth of sub-micron complex oxide structures by amorphous SrTiO_3
P. Morales, M. DiCiano, and J. Y. T. Wei, Applied Physics Letters 86, 192509 (2005).

Scanning tunneling spectroscopy under pulsed spin injection
J. Ngai, et al., Applied Physics Letters 841907 (2004).

Nanoscale high-temperature superconductivity
P. Mohanty, J. Y.T. Wei, V. Ananth, P. Morales, W. Skocpol, Physica C 408–410, 666 (2004).

Spin-Injection Quasiparticle Nonequilibrium in Cuprate/Manganite Heterostructures,

J. Y. T. Wei et al.Journal of Superconductivity 15-1, 67 (2002). 

Tunneling spectroscopy study of spin-polarized quasiparticle injection effects in 
cuprate/manganite heterostructures
J. Y. T. Wei et al., Journal of Applied Physics 85, 5350 (1999). 

Directional tunneling and Andreev reflection on YBa_2Cu_3O_{7-delta} single crystals: 
Predominance of d-wave pairing symmetry verified with the generalized BTK theory
J. Y. T. Wei et al.Physical Review Letters 81, 2542 (1998).

Quasiparticle tunneling spectra of the high-Tc mercury cuprates: implication of the 
d-wave two-dimensional van Hove scenario
J. Y. T. Wei et al., Physical Review B 57, 3650 (1998).

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