# Graduate Research, Awards, & Activities

## graduate program

### Conference Activity

Many of our graduate students gave presentations at the 2009 American Physical Society March Meeting in Pittsburgh, PA.

### Awards and Recognitions

Divakaran Murugesapillai received Donald J. White Teaching Excellence Award for 2009.

Yiming Xu and Marco Almeida received Donald J. White Teaching Excellence Awards for 2007-2008.

Chang-Sheng Mei and Lucas Lindsay won Boston College Teaching Excellence Awards in May 2006.

### Recent Student Publications

W. S. Liu, Q. Y. Zhang, Y. C. Lan, Shuo Chen, X. Yan, Qian Zhang, Hui Wang, D. Z. Wang, Gang Chen, Z. F. Ren, “Thermoelectric property studies on Cu doped n-type CuxBi2Te2.7Se0.3 nanocomposites”, Adv. Energ. Mater. (accepted).

G. Joshi, X. Yan, H. Z. Wang, W. S. Liu, G. Chen, Z. F. Ren, “Enhancement in thermoelectric figure-of-merit of n-type half-Heusler material by nanocomposite approach”, Adv. Energ. Mater. DOI: 10.1002/aenm.201100126 (published online May 3rd, 2011).

D. Kraemer, B. Poudel, H. –P. Feng, J. C. Caylor, B. Yu, X. Yan, Y. Ma, X.W. Wang, D. Z. Wang, A. Muto, K. McEnaney, M. Chiesa, Z. F. Ren, G. Chen, “Solar thermoelectric generators with flat-panel thermal concentration”, Nat. Mater. DOI:10.1038/nmat3013 (published online May 1st, 2011).

X. Yan, G. Joshi, W. S. Liu, Y. C. Lan, H. Wang, S. Y. Lee, J. W. Simonson, S. J. Poon, T. M. Tritt, G. Chen, Z. F. Ren, “Enhanced Thermoelectric Figure-of-Merit of p-type Half-Heuslers”, Nano Lett. 11, 556 (2011).

Chang-Sheng Mei, Lawrence P. Panych, Jing Yuan, Nathan J. McDannold, Lisa H. Treat, Yun Jing, Bruno Madore, “Combining Two-Dimensional Spatially Selective RF Excitation, Parallel Imaging and UNFOLD for Accelerated MR Thermometry Imaging”, Magn Reson Med, DOI: 10.1002/mrm.22788 (2011).

Bruno Madore, Lawrence P. Panych, Chang-Sheng Mei, Jing Yuan, Renxin Chu, “Multi-pathway sequences for MR thermometry”, Magn Reson Med, DOI: 10.1002/mrm.22844 (2011).

Y.-M. Xu, P. Richard, K. Nakayama, T. Kawahara, Y. Sekiba, T. Qian, M. Neupane, S. Souma, T. Sato, T. Takahashi, H. Luo, H.-H. Wen, G.-F. Chen, N.-L. Wang, Z. Wang, Z. Fang, X. Dai, H. Ding. “Fermi surface dichotomy of superconducting gap and pseudogap in underdoped pnictides”. Nature communications (in press) DOI: 10.1038/ncomms1394 (2011).

P. Zhang, P. Richard, T. Qian, Y.-M. Xu, X. Dai and H. Ding. “A precise method for visualizing dispersive features in image plots”, Rev. Sci. Instrum. 82, 043712 (2011).

K. Nakayama, T. Sato, Y.-M. Xu, Z.-H. Pan, P. Richard, H. Ding, H.-H. Wen, K. Kudo, T. Sasaki, N. Kobayashi and T. Takahashi. “Two pseudogaps with different energy scales at the antinode of Bi2Sr2CuO6”, Phys. Rev. B 83, 224509 (2011).

T. Qian, N. Xu, Y.-B. Shi, K. Nakayama, P. Richard, T. Kawahara, T. Sato, T. Takahashi, M. Neupane, Y.-M. Xu, X.-P. Wang, G. Xu, X. Dai, Z. Fang, P. Cheng, H.-H. Wen and H. Ding. “Fermiology of Sr4V2O6Fe2As2: Quasi-nested Fe vs Mott insulating V orbitals”, Phys. Rev. B 83, 140513(R) (2011).

H. Ding, K. Nakayama, P. Richard, S. Souma, T. Sato, T. Takahashi, M. Neupane, Y.-M. Xu, Z.-H. Pan, A.V. Federov, Z. Wang, X. Dai, Z. Fang, G.F. Chen, J.L. Luo, and N.L. Wang. “Electronic structure of optimally doped pnictide Ba0.6K0.4Fe2As2: a comprehensive angle-resolved photoemission spectroscopy investigation”, J. Phys.: Condens. Matter 23, 135701 (2011).

M. Neupane, P. Richard, Y.-M. Xu, K. Nakayama, T. Sato, T. Takahashi, A. V. Fedorov, G. Xu, X. Dai, Z. Fang, Z. Wang, G.-F. Chen, N.-L. Wang, H.-H. Wen, H. Ding. “Electron-Hole asymmetry in superconductivity of pnictides originated from the observed rigid chemical potential shift”, Phys. Rev. B 83, 094522 (2011).

K. Nakayama, T. Sato, P. Richard, Y.-M. Xu, T. Kawahara, K. Umezawa, T. Qian, M. Neupane, G.-F. Chen, H. Ding and T. Takahashi. “Universality of superconducting gaps in overdoped Ba0.3K0.7Fe2As2 observed by angle-resolved photoemission spectroscopy”, Phys. Rev. B 83, 020501(R) (2011).

Y.-M. Xu, Y.-B. Huang, X.-Y. Cui, E. Razzoli, M. Radovic, M. Shi, G.-F. Chen, P. Zheng, N.-L. Wang, C.-L. Zhang, P.-C. Dai, J.-P. Hu, Z.Wang and H. Ding. Observation of a ubiquitous three-dimensional superconducting gap function in optimally doped Ba0.6K0.4Fe2As2. Nature Physics 7, 198-202 (2011).

D. Shrekenhamer, S. Rout, A. Strikwerda, C. Bingham, R. Averitt, S. Sonkusale, and W. Padilla, "High speed terahertz modulation from metamaterials with embedded high electron mobility transistors," Opt. Express 19, 9968-9975 (2011).

Y. Sekiba, T. Sato, K, Nakayama, K. Terashima, P. Richard, J. H. Bowen, H. Ding, Y.-M. Xu, L. J. Li, G. H. Cao, Z.-A. Xu and T. Takahashi. Angle-resolved photoemission study of heavily electron-doped BaFe2-xCoxAs2. Physica C 470, S394-S396 (2010).

X. Yan, B. Poudel, Y. Ma, W. S. Liu, G. Joshi, H. Wang, Y. C. Lan, D. Z. Wang, G. Chen, Z. F. Ren, “Experimental Studies on Anisotropic Thermoelectric Properties and Structures of n-Type Bi2Te2.7Se0.3”, Nano Lett. **10**, 3373 (2010).

H. Tao, C. M. Bingham, A. C. Strikwerda, D. Pilon, D. Shrekenhamer, N. I. Landy, K. Fan, X. Zhang, W. J. Padilla, and R. D. Averitt, "Highly-Flexible Wide Angle of Incidence Terahertz Metamaterial Absorber," *Phys*. *Rev*. *B* (*Rapid Communications*) **78**, 241103R (2008).

J.-H. Ma, Z.-H. Pan, F. C. Niestemski, M. Neupane, Y.-M. Xu, P. Richard, K. Nakayama, T. Sato, T. Takahashi, H.-Q. Luo, L. Fang, H.-H. Wen, Z. Wang, H. Ding, V. Madhavan, "Coexistence of Competing Orders with Two Energy Gaps in Real and Momentum Space in the High Temperature Superconductor Bi2Sr2-xLaxCuO6+," *Phys. Rev. Lett.* **101**, 207002 (2008).

"High-Thermoelectric Performance of Nanostructured Bismuth Antimony Telluride Bulk Alloys," B. Poudel, Q. Hao, Y. Ma, Y. Lan, A. Minnich, B. Yu, X. Yan, D. Wang, A. Muto, D. Vashaee, X. Chen, J. Liu, M. S. Dresselhaus, G. Chen, Z. Ren. *Science* **320**, 634 (2008).

"Three-Phonon Phase Space and Lattice Thermal Conductivity in Semiconductors," L. Lindsay, and D. A. Broido, *J. Phys.: Condens. Matter* **20**, 165209 (2008).

"Intrinsic Lattice Thermal Conductivity of Si/Ge and GaAs/AlAs Superlattices," A. Ward, and D. A. Broido, *Phys. Rev. B* **77**, 245328 (2008).

"Experimental Demonstration of Frequency-Agile Terahertz Metamaterials," H-T. Chen, J. F. O'Hara, A. K. Azad, A. J. Taylo, R. D. Averitt, D. B. Shrekenhamer, and W. J. Padilla.* Nat. Photonics* **2**, 295 (2008).

"Ground State of Magnetic Dipoles on a Two-Dimensional Lattice:

Structural Phases in Complex Plasmas," J. D. Feldmann, G. J. Kalman, P. Hartmann, and M. Rosenberg. *Phys. Rev. Lett.* **100**, 085001 (2008).

"Subwavelength Waveguide for Visible Light," J. Rybczynski, K. Kempa, A. Herczynski, Y. Wang, M. J. Naughton, Z. F. Ren, Z. P. Huang, D. Cai, and M. Giersig.* Appl. Phys. Lett.* **90**, 021104 (2007).

F.C. Niestemski, S. Kunwar, S. Zhou, Shiliang Li, H. Ding, Ziqiang Wang, Pengcheng Dai, V. Madhavan, "A distinct bosonic mode in an electron-doped high-transition-temperature superconductor," *Nature***450**, 1058-1061 (2007).

"Acoustic Attenuation Probe for Fermion Superfluidity in Ultracold Atom Gases," S. Gaudio, B. Mihaila, K. B. Blagoev, K.S. Bedell, and E. Timmermans. *Phys. Rev. Lett.* **98**, 110407 (2007).

"Visible Light Diffraction Studies on Periodically Aligned Arrays of Carbon Nanotubes: Experimental and Theoretical Comparison," J. Rybczynski, K. Kempa, Y. Wang, Z. F. Ren, J. B. Carlson, B. R. Kimball, and G. Benham. *Appl. Phys. Lett.* **88**, 203122 (2006).

"Kink Formation and Motion in Carbon Nanotubes at High Temperatures," J.Y. Huang, S. Chen, Z. F. Ren, Z. Q. Wang, D. Z. Wang, M. Vaziri, Z. Suo, G. Chen, and M. S. Dresselhaus.* Phys. Rev. Lett*.** 97**, 075501 (2006).

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