DAVID HSIEH, Pappalardo
Fellow in Physics: 2009-12
Research Interests
David Hsieh’s research focuses on exotic quantum states of matter that are realized in solid state systems, such as topological quantum spin Hall insulators, high temperature superconductors and highly frustrated magnets. In particular, he is interested in using advanced scattering based probes combining spin, spatial and temporal resolutions matching those of fundamental quantum processes to understand the microscopic mechanisms giving rise to these quantum states.
One direction of Hsieh’s research is centered on the discovery and manipulation of topological insulators, a spin analogue of the quantum Hall state that exists in the absence of any external magnetic field. Unlike common ordered states of condensed matter that are described within the Ginzburg-Landau framework and can be experimentally identified by some local order parameter, topological insulators can only be identified by a new set of quantum numbers such as edge states and Berry’s phases. Hsieh is working on experimental methods of measuring these so-called topological quantum numbers, controlling topological phase transitions, as well as exploring their possibility for realizing axion electrodynamics, as has been theoretically predicted.
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Biographical Sketch
David Hsieh completed his Ph.D. at Princeton University with Prof. Zahid Hasan. His work focused upon spin- and angle-resolved photoemission spectroscopies of topologically ordered phases of matter and novel superconductors, as well as on neutron scattering studies of highly frustrated magnets. He earned his B.S. in physics and mathematics from Stanford University in 2003, where he worked on cold atom experiments with Prof. Steven Chu’s group.
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Selected Publications
D. Hsieh, Y. Xia, L. Wray, D. Qian, A. Pal, J. H. Dil, F. Meier, J. Osterwalder, G. Bihlmayer, C. L. Kane, Y. S. Hor, R. J. Cava and M. Z. Hasan. “Observation of unconventional quantum spin textures in topologically ordered materials”. Science, in press (2009).
D. Hsieh, Y. Xia, L. Wray, D. Qian, K. K. Gomes, A. Yazdani, G. F. Chen, J. L. Luo, N. L. Wang and M. Z. Hasan. “Experimental determination of the electronic ground state of antiferromagnetic parent iron pnictides”. Preprint at < http://arxiv.org/abs/0812.2289> (2008).
D. Hsieh, D. Qian, L. Wray, Y. Xia, Y. S. Hor, R. J. Cava and M. Z. Hasan. “A topological Dirac insulator in a quantum spin Hall phase”. Nature 452, 970 (2008).
D. Hsieh, D. Qian, R. F. Berger, R. J. Cava, J. W. Lynn, Q. Huang and M. Z. Hasan. “Unconventional spin order in the triangular lattice system NaCrO2: A neutron scattering study”. Physica B 403, 1341 (2008).
D. Hsieh, D. Qian, R. F. Berger, R. J. Cava, J. W. Lynn, Q. Huang and M. Z. Hasan. “Magnetic excitations in triangular lattice NaCrO2”. J. Phys. Chem. Solids 69, 3174 (2008).
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