Modulation Doping of a Mott Quantum Well by a Proximate Polar Discontinuity (2008)
Higuchi, T., Hotta, Y., Susaki, T., Fujimori, A., Hwang, H. Y.
We present evidence for hole injection into LaAlO3/LaVO3/LaAlO3 quantum wells near a polar surface of LaAlO3 (001). As the surface is brought in proximity to the LaVO3 layer, an exponential drop in...
Wadati, H., Hawthorn, D. G., Geck, J., Higuchi, T., Hikita, Y., Hwang, H. Y., ...
We investigated the electronic structure of the SrTiO$_3$/LaAlO$_3$ superlattice (SL) by resonant soft x-ray scattering. The (003) peak, which is forbidden for our "ideal" SL structure, was observed...
Remote hole-doping of Mott insulators on the nanometer scale (2008)
Takizawa, M., Hotta, Y., Susaki, T., Ishida, Y., Wadati, H., Takata, Y., ...
At interfaces between polar and nonpolar perovskite oxides, an unusual electron-doping has been previously observed, due to electronic reconstructions. We report on remote hole-doping at an interface...
Hikita, Y., Kourkoutis, L. Fitting, Susaki, T., Muller, D. A., Takagi, H., Hwang, H. Y.
We observed a strong modulation in the current-voltage characteristics of SrRuO$_3$/Nb:SrTiO$_3$ Schottky junctions by Mn substitution in SrRuO$_3$, which induces a metal-insulator transition in...
Vanishing Hall Coefficient in the Extreme Quantum Limit in Photocarrier-Doped SrTiO3 (2008)
Kozuka, Y., Susaki, T., Hwang, H. Y.
We have investigated the extreme quantum limit of photogenerated electrons in quantum paraelectric SrTiO3. This regime is distinct from conventional semiconductors, due to the large electron...
Polar Discontinuity Doping of the LaVO_3/SrTiO_3 Interface (2007)
Hotta, Y., Susaki, T., Hwang, H. Y.
We have investigated the transport properties of LaVO_3/SrTiO_3 Mott insulator/band insulator heterointerfaces for various configurations. The (001)-oriented n-type VO_2/LaO/TiO_2 polar discontinuity...
Temperature Dependent Polarity Reversal in Au/Nb:SrTiO3 Schottky Junctions (2007)
Susaki, T., Kozuka, Y., Tateyama, Y., Hwang, H. Y.
We have observed temperature-dependent reversal of the rectifying polarity in Au/Nb:SrTiO3 Schottky junctions. By simulating current-voltage characteristics we have found that the permittivity of...
Kozuka, Y., Hikita, Y., Susaki, T., Hwang, H. Y.
We report magnetotransport properties of photogenerated electrons in undoped SrTiO$_3$ single crystals under ultraviolet illumination down to 2 K. By tuning the light intensity, the steady state...
Hard x-ray photoemission study of LaAlO3/LaVO3 multilayers (2007)
Wadati, H., Hotta, Y., Fujimori, A., Susaki, T., Hwang, H. Y., Takata, Y., ...
We have studied the electronic structure of multilayers composed of a band insulator LaAlO$_3$ (LAO) and a Mott insulator LaVO$_3$ (LVO) by means of hard x-ray photoemission spectroscopy, which has a...
Characterization of the Schottky Barrier in SrRuO3/Nb:SrTiO3 Junctions (2007)
Hikita, Y., Kozuka, Y., Susaki, T., Takagi, H., Hwang, H. Y.
Internal photoemission spectroscopy was used to determine the Schottky barrier height in rectifying SrRuO3/Nb-doped SrTiO3 junctions for 0.01 wt % and 0.5 wt % Nb concentrations. Good agreement was...
Nanometer scale electronic reconstruction at the interface between LaVO3 and LaVO4 (2007)
Kourkoutis, L. Fitting, Hotta, Y., Susaki, T., Hwang, H. Y., Muller, D. A.
Electrons at interfaces, driven to minimize their free energy, are distributed differently than in bulk. This can be dramatic at interfaces involving heterovalent compounds. Here we profile an abrupt...
Interface Magnetoresistance in Manganite-Titanate Heterojunctions (2006)
Susaki, T., Nakagawa, N., Hwang, H. Y.
We have found that the current- voltage characteristics of La0.7Sr0.3MnO3(-delta)/Nb:SrTiO3 rectifying junctions are quantitatively well-described by (thermally-assisted) tunneling with an...
Electronic structure of the Mott insulator LaVO3 in a quantum well geometry (2006)
Hotta, Y., Wadati, H., Fujimori, A., Susaki, T., Hwang, H. Y.
We used x-ray photoemission spectroscopy to investigate the electronic structure of the Mott insulator LaVO3 embedded in LaAlO3. By limiting the upper layer of LaAlO3 to 3 unit cells, the underlying...
Lattice polarization effects on electron-gas charge densities in ionic superlattices (2006)
Hamann, D. R., Muller, D. A., Hwang, H. Y.
The atomic-level control achievable in artificially-structured oxide superlattices provides a unique opportunity to explore interface phases of matter including high-density 2D electron gases....
Magnetocapacitance and exponential magnetoresistance in manganite-titanate heterojunctions (2004)
Nakagawa, N., Asai, M., Mukunoki, Y., Susaki, T., Hwang, H. Y.
We present a rectifying manganite-titanate heterojunction exhibiting a magnetic field tunable depletion layer. This creates a large positive magnetocapacitance, a direct measure of the field-induced...
Efficient Rule-Based Attribute-Oriented Induction for Data Mining (2000)
David W. Cheung, H. Y. Hwang, Ada W. Fu, Jiawei Han
. Data mining has become an important technique which has tremendous potential in many commercial and industrial applications. Attribute-oriented induction is a powerful mining technique and has been...
Magnon Damping by magnon-phonon coupling in Manganese Perovskites (1999)
Dai, Pengcheng, Hwang, H. Y., Zhang, Jiandi, Fernandez-Baca, J. A., Cheong, S-W., Kloc, C., ...
Inelastic neutron scattering was used to systematically investigate the spin-wave excitations (magnons) in ferromagnetic manganese perovskites. In spite of the large differences in the Curie...
Softening and Broadening of the Zone Boundary Magnons in Pr0.63Sr0.37MnO3 (1997)
Hwang, H. Y., Dai, P., Cheong, S-W., Aeppli, G., Tennant, D. A.
We have studied the spin dynamics in Pr$_{0.63}$Sr$_{0.37}$MnO$_3$ above and below the Curie temperature $T_C=301$ K. Three distinct new features have been observed: a softening of the magnon...
Evolution of the low-frequency spin dynamics in ferromagnetic manganites (1997)
Fernandez-Baca, J. A., Dai, P., Hwang, H. Y., Cheong, S-W., Kloc, C.
Elastic and inelastic neutron scattering was used to study two ferromagnetic manganites A$_{1-x}$B$_{x}$MnO$_3$ (x $\approx$ 0.3) with $T_c$=197.9 K and 300.9 K. The spin dynamical behavior of these...
Pressure effects on the magnetoresistance in doped manganese perovskites (1995)
Hwang, H.Y., Palstra, T.T.M., Cheong, S-W., Batlogg, B.
We present a detailed study on the effects of applied hydrostatic pressure on the magnetoresistance in doped LaMnO3 at fixed doping level. In all cases, the application of external pressure...
Wauters, J, Bijnens, N, Dendooven, P, Huyse, M, Hwang, H Y, Reusen, G, ...
Wilson, A, Leclerc, D, Saberi, F, Campeau, E, Hwang, H Y, Shane, B, ...
Methionine synthase (MS) catalyses the methylation of homocysteine to methionine and requires the vitamin B12 derivative, methylcobalamin, as cofactor. We and others have recently cloned cDNAs for MS...
Wilson, A, Leclerc, D, Saberi, F, Campeau, E, Hwang, H Y, Shane, B, ...
Methionine synthase (MS) catalyses the methylation of homocysteine to methionine and requires the vitamin B12 derivative, methylcobalamin, as cofactor. We and others have recently cloned cDNAs for MS...