Harold Y. Hwang / Associate Professor / Division of Transdisciplinary Sciences Department of Advanced Materials Science / / Solid State Physics, Ultrafast Laser Spectroscopy Career Summary 1993 B.S. in Physics, Massachusetts Institute of Technology, 1993 B.S. in Electrical Engineering, Massachusetts Institute of Technology, 1993 M.S. in Electrical Engineering, Massachusetts Institute of Technology, 1996 Member of Technical Staff, Materials Physics Research, Bell Laboratories, 1997 Ph.D. in Physics, Princeton University, 2003 Assoc. Professor, Dept. of Advanced Materials Science, University of Tokyo Educational Activities Research Activities 　A general area of exploration has been the unusual physical properties of the doped transition metal oxides. We demonstrated the transport consequences of various phase transitions in nickelates and cuprates. We established electronic bandwidth tuning by static/dynamic lattice distortions in perovskite manganites. This work led to studies establishing spin-polarized tunneling in half-metallic oxide ferromagnets. 　We have been exploring the use of chalcogenide glasses for photonic devices. Two examples include the development of thin film waveguides for nonlinear optical response, and the use of chalcogenide lateral claddings for high-speed electro-optic devices. 　In the last few years, we have been focusing on oxide heterostructures, in particular the electronic structure at interfaces and in confined geometries. We recently demonstrated the ability to fabricate structures with atomic precision. We are now using these techniques to create novel charge states inaccessible in bulk materials.   Literature 1） ""Scaling of the Temperature Dependent Hall Effect in La2-xSrxCuO4,"" H. Y. Hwang et al., Physical Review Letters 72, 2636 (1994). 2） ""Charge-Ordered States in (La,Sr)2NiO4 for Hole Concentrations nh = 1/3 and 1/2,"" S-W. Cheong et al., Physical Review B 49, 7088 (1994). 3） ""Lattice Effects on the Magnetoresistance in Doped LaMnO3,"" H. Y. Hwang et al., Phys. Rev. Lett. 75, 914 (1995). 4） ""Spin-Polarized Intergrain Tunneling in La2/3Sr1/3MnO3,"" H. Y. Hwang et al., Physical Review Letters 77, 2041 (1996). 5） ""Low-Field Magnetoresistance in the Pyrochlore Tl2Mn2O7,"" H. Y. Hwang and S-W. Cheong, Nature 389, 942 (1997). 6） ""Enhanced Intergrain Tunneling Magnetoresistance in Half-Metallic CrO2 Films,"" H. Y. Hwang and S-W. Cheong, Science 278, 1607 (1997). 7） ""Softening and Broadening of the Zone Boundary Magnons in Pr0.63Sr0.37MnO3,"" H. Y. Hwang et al., Physical Review Letters 80, 1316 (1998). 8） ""Quantum Cascade Lasers with Low-loss Chalcogenide Lateral Waveguides,"" C. Gmachl et al., IEEE Photonics Technology Letters 13, 182 (2001). 9） ""Self-phase Modulation in Chalcogenide Waveguides,"" S. Spaelter et al., Optics Letters 27, 363 (2002). 10） ""Artificial Charge Modulation in Atomic-Scale Perovskite Titanate Superlattices,"" A. Ohtomo et al., Nature 419, 378 (2002). Other Activities 　Symposium organizer, ""Complex Oxide Heteroepitaxy,"" MRS Fall 2001., Symposium organizer, ""Magnetic Oxides and Oxide Devices,"" MRS Fall 1998., Member, American Physical Society, Materials Research Society. Future Plan 　We wish to continue our research probing strongly correlated electrons at artificial interfaces and in confined systems, leading to studies of the electrical, optical, and magnetic response of oxide heterostructures in device geometries. Messages to Students 　If you are interested in materials physics research on complex oxide heterostructures, in an international environment, as well as teaching some Japanese, come join us!