Lu, Xin, Park, W. K., Yuan, H. Q., Chen, G. F., Luo, G. L., Wang, N. L., ...
Point-contact Andreev reflection spectroscopy (PCARS) is applied to investigate the gap structure in iron pnictide single crystal superconductors of the AFe_2As_2 (A=Ba, Sr) family ("Fe-122"). The...
Optical spectroscopy study on single crystalline LaFeAsO (2009)
Chen, Z. G., Yuan, R. H., Dong, T., Wang, N. L.
Millimeter sized single crystals of LaFeAsO were grown from NaAs flux and the in-plane optical properties were studied over a wide frequency range. A significant electronic correlation effect was...
Observation of Dirac Cone Electronic Dispersion in BaFe2As2 (2009)
Richard, P., Nakayama, K., Sato, T., Neupane, M., Bowen, J. H., ...
We performed an angle-resolved photoemission spectroscopy study of BaFe2As2, which is the parent compound of the so-called 122 phase of the iron-pnictide high-temperature superconductors. We reveal...
Lattice distortion and magnetic quantum phase transition in CeFeAs(1-x)P(x)O (2009)
De La Cruz, Clarina, Hu, W. Z., Li, Shiliang, Huang, Q., Lynn, J. W., Green, M. A., ...
We use neutron scattering to show that replacing the larger arsenic with smaller phosphorus in CeFeAs(1-x)P(x)O simultaneously suppresses the AF order and orthorhombic distortion near x = 0.4,...
Nakayama, K., Sato, T., Richard, P., Kawahara, T., Sekiba, Y., Qian, T., ...
We have performed high-resolution angle-resolved photoemission spectroscopy of iron-chalcogenide superconductor Fe1.03Te0.7Se0.3 (Tc = 13 K) to investigate the electronic structure relevant to...
Optical study on the spin-density wave properties in single crystalline Na$_{1-\delta}$FeAs (2009)
Hu, W. Z., Li, G., Zheng, P., Chen, G. F., Luo, J. L., Wang, N. L.
We report an optical investigation on the in-plane charge dynamics for Na$_{1-\delta}$FeAs single crystal. A clear optical evidence for the spin-density wave (SDW) gap is observed. As the...
Xia, Y., Qian, D., Wray, L., Hsieh, D., Chen, G. F., Luo, J. L., ...
We report the first photoemission study of Fe$_{1+x}$Te - the host compound of the newly discovered iron-chalcogenide superconductors (maximum T$_c$ $\sim$ 27K). Our results reveal a pair of nearly...
Mayaffre, H., Horvatic, M., Berthier, C., Zhang, X. D., Wu, W., ...
In Ba(Fe0.95Co0.05)2As2 all of the 75As NMR intensity at the paramagnetic resonance position vanishes abruptly below Tonset(SDW)=56 K, indicating that magnetic (spin density wave) order is present in...
Chen, Z. G., Xu, G., Hu, W. Z., Zhang, X. D., Zheng, P., Chen, G. F., ...
BaNi$_2$As$_2$ exhibits a first order structural transition at 130 K. Understanding this structural transition is a crucial step towards understanding the electronic properties of the material. We...
Structural and magnetic phase transitions in Na$_{1-\delta}$FeAs (2009)
Li, Shiliang, De La Cruz, Clarina, Huang, Q., Chen, G. F., Lou, J. L., ...
We use neutron scattering to study the spin and lattice structures of single crystal and powder samples of Na$_{1-\delta}$FeAs ($T_c = 23$ K). On cooling from room temperature, the system goes...
Nonequilibrium quasiparticle dynamics in single crystals of Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ (2009)
Torchinsky, Darius H, Chen, G. F., Luo, J. L., Wang, N. L., Gedik, Nuh
We report on the quasiparticle dynamics in Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ ($T_c = 37 K$) as a function of temperature and excitation density. Quasiparticles are injected into single crystal samples...
Possible high temperature superconductivity in Ti-doped A-Sc-Fe-As-O (A= Ca, Sr) system (2009)
Chen, G. F., Yang, H. X., Li, J. Q., Zheng, P., Luo, J. L., ...
We report a systematic study on the effect of partial substitution of Sc$^{3+}$ by Ti$^{4+}$ in Sr$_{2}$ScFeAsO$_{3}$, Ca$_{2}$ScFeAsO$_{3}$ and Sr$_{3}$Sc$_{2}$Fe$_{2}$As$_{2}$O$_{5}$ on their...
Electronic Structure of the BaFe$_2$As$_2$ Family of Iron Pnictides (2009)
Yi, M., Lu, D. H., Analytis, J. G., ...
We use high resolution angle-resolved photoemission spectroscopy to study the band structure and Fermi surface topology of the BaFe$_2$As$_2$ iron pnictides. We observe two electron bands and two...
Multiple phase transitions in single-crystalline Na$_{1-\delta}$FeAs (2009)
Chen, G. F., Hu, W. Z., Luo, J. L., Wang, N. L.
Specific heat, resistivity, susceptibility, Hall coefficient and optical measurements were performed on the high quality single crystalline Na$_{1-\delta}$FeAs. This compound is found to undergo...
Optical and Raman spectroscopy studies on Fe-based superconductors (2009)
Hu, W. Z., Zhang, Q. M., Wang, N. L.
A brief review of optical and Raman studies on the Fe-based superconductors is given, with special emphasis on the competing phenomenon in this system. Optical investigations on ReFeAsO...
Fermi surface topology and low-lying quasiparticle structure of magnetically ordered Fe1+xTe (2009)
Xia, Y., Qian, D., Wray, L., Hsieh, D., Chen, G. F., Luo, J. L., ...
We report the first photoemission study of Fe1+xTe - the host compound of the newly discovered iron-chalcogenide superconductors. Our results reveal a pair of nearly electron- hole compensated Fermi...
Zhou, Yu-Rong, Li, Yan-Rong, Zuo, Jun-Wei, Liu, Rui-Yuan, Su, Shao-Kui, Chen, G. F., ...
We have made a phase-sensitive measurement on the corner junction of the iron-based superconductor BaFe1.8Co0.2As2, and observed the typical Fraunhofer-like diffraction pattern. The result suggests...
Wray, L., Qian, D., Hsieh, D., Xia, Y., Li, L., Checkelsky, J. G., ...
We present a systematic angle-resolved photoemission spectroscopic study of the high-Tc superconductor class (Sr/Ba){1-x}(K/Na)xFe2As2. By utilizing a photon-energy-modulation contrast and scattering...
Experimental determination of the microscopic origin of magnetism in parent iron pnictides (2008)
Hsieh, D., Xia, Y., Wray, L., Qian, D., Gomes, K., Yazdani, A., ...
Like high Tc cuprates, the newly discovered iron based superconductors lie in close proximity to a magnetically ordered parent phase. However, while the magnetic order in parent cuprates is known to...
Nakayama, K., Sato, T., Richard, P., Sekiba, Y., Souma, S., ...
We have performed high-resolution angle-resolved photoemission spectroscopy on the optimally-doped Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ compound and determined the accurate momentum dependence of the...
Ding, H., Nakayama, K., Richard, P., Souma, S., Sato, T., Takahashi, T., ...
We have conducted a comprehensive angle-resolved photoemission study on the normal state electronic structure of the Fe-based superconductor Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$. We have identified four...
Large quasiparticle thermal Hall conductivity in the superconductor $\rm Ba_{1-x}K_xFe_2As_2$ (2008)
Checkelsky, J. G., Li, Lu, Chen, G. F., Luo, J. L., Wang, N. L., Ong, N. P.
Both the thermal conductivity $\kappa_{xx}$ and thermal Hall conductivity $\kappa_{xy}$ in $\rm Ba_{1-x}K_xFe_2As_2$ display large peak anomalies in the superconducting state. The anomalies imply...
Structural features and tetragonal-orthorhombic phase transition in SrFe2As2 and CaFe2As2 (2008)
Ma, C., Yang, H. X., Tian, H. F., Shi, H. L, Lu, J. B., Wang, Z. W., ...
The structural properties of the SrFe2As2 and CaFe2As2 compounds have been extensively analyzed by transmission electron microscopy (TEM) from room temperature down to 20K. The experimental results...
Raman phonons of $\alpha$-FeTe and Fe$_{1.03}$Se$_{0.3}$Te$_{0.7}$ single crystals (2008)
Xia, Tian-Long, Hou, D., Zhao, S. C., Zhang, A. M., Chen, G. F., Luo, J. L., ...
Polarized Raman scattering spectra of nonsuperconducting $\alpha$-FeTe and newly discovered superconducting Fe$_{1.03}$Se$_{0.3}$Te$_{0.7}$ single crystals are measured at room temperature. Phonon...
Chen, G. F., Chen, Z. G., Dong, J., Hu, W. Z., Li, G., Zhang, X. D., ...
We report on a comprehensive study of the transport, specific heat, magnetic susceptibility and optical spectroscopy on single crystal of Fe$_{1.05}$Te. We confirm that Fe$_{1.05}$Te undergoes a...
Band Structure and Fermi Surface of an Extremely Overdoped Iron-Based Superconductor KFe2As2 (2008)
Sato, T., Nakayama, K., Sekiba, Y., Richard, P., Souma, S., ...
We have performed high-resolution angle-resolved photoemission spectroscopy on heavily overdoped KFe_2As_2 (transition temperature (Tc = 3 K). We observed several renormalized bands near the Fermi...
Two superconducting gaps in LaFeAsO0.92F0.08 revealed by 75As nuclear quadrupole resonance (2008)
Kawasaki, S., Shimada, K., Chen, G. F., Luo, J. L., Wang, N. L., Zheng, Guo-qing
We report $^{75}$As nuclear quadrupole resonance (NQR) studies on superconducting oxypnictide LaFeAsO$_{0.92}$F$_{0.08}$ ($T_{\rm c}$ = 23 K). The temperature dependence of the spin lattice...
Spin and lattice structures of single-crystalline SrFe2As2 (2008)
Zhao, J., Ratcliff, W., Lynn, J. W., Chen, G. F., Luo, J. L., Wang, N. L., ...
Doping evoluton of antiferromagnetic order and structural distortion in LaFeAsO$_{1-x}$F$_x$ (2008)
Huang, Q., Zhao, Jun, Lynn, J. W., Chen, G. F., Luo, J. L., Wang, N. L., ...
We use neutron scattering to study the structural distortion and antiferromagnetic (AFM) order in LaFeAsO$_{1-x}$F$_{x}$ as the system is doped with fluorine (F) to induce superconductivity. In the...
Competing energy scales in iron-based layered (Ba,K)Fe2As2 superconductors (2008)
Chia, Elbert E. M., Talbayev, D., Yuan, H. Q., Park, T., Thompson, J. D., ...
Recent discovery of superconductivity in Fe-based compounds, the only class of non-cuprate materials with superconducting transition temperatures (Tc) larger than 40 K, has generated tremendous...
Low energy spin waves and magnetic interactions in SrFe$_2$As$_2$ (2008)
Zhao, Jun, Yao, Dao-Xin, Li, Shiliang, Hong, Tao, Chen, Y., Chang, S., ...
We report inelastic neutron scattering studies of magnetic excitations in antiferromagnetically ordered SrFe$_{2}$As$_{2}$ ($T_{N}=220$ K), the parent compound of the FeAs-based superconductors. At...
Wray, L., Qian, D., Hsieh, D., Xia, Y., Li, L., Checkelsky, J. G., ...
We present a systematic photoemission study of the newly discovered high Tc superconductor class (Sr/Ba)1-xKxFe2As2. By utilizing a unique photon energy range and scattering geometry we resolve the...
Richard, P., Sato, T., Nakayama, K., Souma, S., Takahashi, T., ...
We have performed an angle-resolved photoemission spectroscopy study of the new superconductor Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ in the low energy range. We report the observation of an anomaly around...
Goko, T., Aczel, A. A., Baggio-Saitovitch, E., Bud'ko, S. L., Canfield, P. C., Carlo, J. P., ...
The recent discovery and subsequent developments of FeAs-based superconductors have presented novel challenges and opportunities in the quest for superconducting mechanisms in correlated-electron...
Adesso, Maria G., Zola, Danilo, Luo, Jianlin, Chen, G F., Li, Zhend, Wang, N. L., ...
Fundamental and higher harmonics of the AC magnetic susceptibility have been measured on a LaO_0.92F_0.08FeAs sample as a function of the temperature, at various amplitudes and frequencies of the AC...
Evidence for the band broadening across the ferromagnetic transition in Cr$_{1/3}$NbSe$_2$ (2008)
Hu, W. Z., Wang, G. T., Hu, Rongwei, Petrovic, C., Morosan, E., ...
The electronic structure of Cr$_{1/3}$NbSe$_2$ is studied via optical spectroscopy. We observe two low-energy interband transitions in the paramagnetic phase, which split into four peaks as the...
Chi, Songxue, Adroja, D. T., Guidi, T., Bewley, R., Li, Shiliang, Zhao, Jun, ...
We use inelastic neutron scattering to study the crystalline electric field (CEF) excitations of Ce$^{3+}$ in CeFeAsO$_{1-x}$F$_{x}$($x=0,0.16$). For nonsuperconducting CeFeAsO, the Ce CEF levels...
Nearly Isotropic superconductivity in (Ba,K)Fe2As2 (2008)
Yuan, H. Q., Singleton, J., Balakirev, F. F., Baily, S. A., Chen, G. F., Luo, J. L., ...
Superconductivity was recently observed in the iron-arsenic-based compounds with a superconducting transition temperature (Tc) as high as 56K [1-7], naturally raising comparisons with the high Tc...
Aczel, A. A., Baggio-Saitovitch, E., Budko, S. L., Canfield, P. C., Carlo, J. P., Chen, G. F., ...
Zero-field (ZF) muon spin relaxation ($\mu$SR) measurements have revealed static commensurate magnetic order of Fe moments in NdOFeAs below $T_{N} \sim 135$ K, with the ordered moment size nearly...
Spin and Lattice Structure of Single Crystal SrFe2As2 (2008)
Zhao, Jun, Ratcliff II, W., Lynn, J. W., Chen, G. F., Luo, J. L., Wang, N. L., ...
We use neutron scattering to study the spin and lattice structure on single crystals of SrFe2As2, the parent compound of the FeAs based superconductor (Sr,K)Fe2As2. We find that SrFe2As2 exhibits an...
Li, G., Hu, W. Z., Dong, J., Li, Z., Zheng, P., Chen, G. F., ...
We performed optical spectroscopy measurement on a superconducting Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystal with T$_c$=37 K. Formation of the superconducting energy gaps in the far-infared...
Magnetic Order of the Iron Spins in NdOFeAs (2008)
Chen, Ying, Lynn, J. W., Li, J., Li, G., Chen, G. F., Luo, J. L., ...
Polarized and unpolarized neutron diffraction measurements have been carried out to investigate the iron magnetic order in undoped NdOFeAs. Antiferromagnetic order is observed below 141(6) K, which...
Zhao, Lin, Liu, Haiyun, Zhang, Wentao, Meng, Jianqiao, Jia, Xiaowen, Liu, Guodong, ...
High resolution angle-resolved photoemission measurements have been carried out to study the superconducting gap in the (Ba0.6K0.4)Fe2As2 superconductor with Tc=35 K. Two hole-like Fermi surface...
Observation of Fermi-surface-dependent nodeless superconducting gaps in Ba0.6K0.4Fe2As2 (2008)
Ding, H., Richard, P., Nakayama, K., Sugawara, T., Arakane, T., Sekiba, Y., ...
The recent discovery of superconductivity in iron-arsenic compounds below a transition temperature (Tc) as high as 55K ended the monopoly of copper oxides (cuprates) in the family of high-Tc...
Liu, Haiyun, Zhang, Wentao, Zhao, Lin, Jia, Xiaowen, Meng, Jianqiao, Liu, Guodong, ...
High resolution angle-resolved photoemission measurements have been carried out on (Sr,K)Fe$_2$As$_2$ superconductor (Tc=21 K). Three hole-like Fermi surface sheets are clearly resolved for the first...
Scanning tunneling microscopy of the 32 K superconductor (Sr1-xKx)Fe2As2 (2008)
Boyer, M. C., Chatterjee, Kamalesh, Wise, W. D., Chen, G. F., Luo, J. L., Wang, N. L., ...
The discovery of high temperature superconductivity in La[O1-xFx]FeAs at the beginning of this year [1] has generated much excitement and has led to the rapid discovery of similar compounds with as...
Zhao, Jun, Huang, Q., De La Cruz, Clarina, Li, Shiliang, Lynn, J. W., Chen, Y., ...
We use neutron scattering to study the structural and magnetic phase transitions in the iron pnictides CeFeAsO1-xFx as the system is tuned from a semimetal to a high-transition-temperature (high-Tc)...
Chen, G. F., Li, Z., Dong, J., Li, G., Hu, W. Z., Zhang, X. D., ...
We have successfully grown high quality single crystals of SrFe$_2$As$_2$ and A$_{0.6}$K$_{0.4}$Fe$_2$As$_2$(A=Sr, Ba) using flux method. The resistivity, specific heat and Hall coefficient have been...
Hu, W. Z., Dong, J., Li, G., Li, Z., Zheng, P., Chen, G. F., ...
We performed optical spectroscopy measurement on single crystals of BaFe$_2$As$_2$ and SrFe$_2$As$_2$, the parent compounds of FeAs based superconductors. Both are found to be quite metallic with...
Superconductivity in hole-doped (Sr$_{1-x}$K$_x$)Fe$_2$As$_2$ (2008)
Chen, G. F., Li, Z., Li, G., Hu, W. Z., Dong, J., Zhang, X. D., ...
A series of layered (Sr$_{1-x}$K$_x$)Fe$_2$As$_2$ compounds with nominal x=0 to 0.40 are synthesized by solid state reaction method. Similar to other parent compounds of iron-based pnictide...
Raman spectra in iron-based quaternary CeO$_{1-x}$F$_x$FeAs and LaO$_{1-x}$F$_x$FeAs (2008)
Zhao, S. C., Hou, D., Wu, Y., Xia, T. L., Zhang, A. M., Chen, G. F., ...
Raman spectra have been measured on iron-based quaternary CeO$_{1-x}$F$_x$FeAs and LaO$_{1-x}$F$_x$FeAs with varying fluorine doping at room temperatures. A group analysis has been made to clarify...
Jia, Xiaowen, Liu, Haiyun, Zhang, Wentao, Zhao, Lin, Meng, Jianqiao, Liu, Guodong, ...
High resolution photoemission measurements have been carried out on non-superconducting LaOFeAs parent compound and various superconducting R(O1-xFx)FeAs (R=La, Ce and Pr) compounds. We found that...
Liu, Haiyun, Jia, Xiaowen, Zhang, Wentao, Zhao, Lin, Meng, Jianqiao, Liu, Guodong, ...
High resolution photoemission measurements have been carried out on non-superconducting SmOFeAs parent compound and superconducting Sm(O$_{1-x}$F$_x$)FeAs (x=0.12, and 0.15) compounds. The...
Carlo, J. P., Uemura, Y. J., Goko, T., MacDougall, G. J., Rodriguez, J. A., Yu, W., ...
Muon spin relaxation (MuSR) measurements in iron oxy-pnictide systems have revealed: (1) commensurate long-range order in undoped LaOFeAs; (2) Bessel function line shape in La(O0.97F0.03)FeAs which...
Nernst effect of the new iron-based superconductor LaO$_{1-x}$F$_{x}$FeAs (2008)
Zhu, Z. W., Xu, Z. A., Lin, X., Cao, G. H., Feng, C. M., Chen, G. F., ...
We report the first Nernst effect measurement on the new iron-based superconductor LaO$_{1-x}$F$_{x}$FeAs $(x=0.1)$. In the normal state, the Nernst signal is negative and very small. Below $T_{c}$ a...
Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems (2008)
De La Cruz, Clarina, Huang, Q., Lynn, J. W., Li, Jiying, Ratcliff II, W., Zarestky, J. L., ...
In high-transition temperature (high-Tc) copper oxides, it is generally believed that antiferromagnetism plays a fundamental role in the superconducting mechanism because superconductivity occurs...
Chen, G. F., Li, Z., Wu, D., Dong, J., Li, G., Hu, W. Z., ...
Different element substitution effects in transition metal oxypnictide Re(O$_{1-x}$F$_x$)TAs with Re=La, Ce, Nd, Eu, Gd, Tm, T=Fe, Ni, Ru, were studied. Similar to the La- or Ce-based systems, we...
Chen, G. F., Li, Z., Wu, D., Li, G., Hu, W. Z., Dong, J., ...
A series of layered CeO$_{1-x}$F$_x$FeAs compounds with x=0 to 0.20 are synthesized by solid state reaction method. Similar to the LaOFeAs, the pure CeOFeAs shows a strong resistivity anomaly near...
Competing Orders and Spin-Density-Wave Instability in La(O$_{1-x}$F$_x$)FeAs (2008)
Dong, J., Zhang, H. J., Xu, G., Li, Z., Li, G., Hu, W. Z., ...
The interplay between different ordered phases, such as superconducting, charge or spin ordered phases, is of central interest in condensed matter physics. The very recent discovery of...
Strong-coupling superconductivity in layered nickel-based LaO$_{1-x}$F$_x$NiAs (2008)
Li, Z., Chen, G. F., Dong, J., Li, G., Hu, W. Z., Wu, D., ...
A series of layered nickel-based LaO$_{1-x}$F$_x$NiAs compounds with x=0 to 0.15 are synthesized by solid state reactions. The pure LaONiAs exhibits bulk superconductivity with Tc $\sim$ 2.75 K....
Superconducting properties of Fe-based layered superconductor LaO$_{0.9}$F$_{0.1-\delta}$FeAs (2008)
Chen, G. F., Li, Z., Li, G., Zhou, J., Wu, D., Dong, J., ...
We have employed a new route to synthesize single phase F-doped LaOFeAs compound and confirmed the superconductivity above 20 K in this Fe-based system. We show that the new superconductor has a...
Phonon softening and "forbidden" mode observed by Raman scattering in Na0.5CoO2 (2008)
Zhang, Q. M., An, M., Yuan, S. K., Wu, Y., Wu, D., Luo, J. L., ...
Polarized Raman scattering measurements have been performed on Na0.5CoO2 single crystal from 8 to 305 K. Both the A1g and E1g phonon modes show a softening below Tc1 ~ 83 K. Additionally, the A1g...
Low Energy Spin Waves and Magnetic Interactions in SrFe2As2 (2008)
Zhao, J., Yao, D. X., Li, S. L., Hong, T., Chen, Y., Chang, S., ...
We report inelastic neutron scattering studies of magnetic excitations in antiferromagnetically ordered SrFe2As2 (TN=200â"220 K), the parent compound of the FeAs-based superconductors. At low...
Anomalous metallic state of Cu$_{0.07}$TiSe$_2$: an optical spectroscopy study (2007)
Li, G., Hu, W. Z., Dong, J., Qian, D., Hsieh, D., Hasan, M. Z., ...
We report an optical spectroscopy study on the newly discovered superconductor Cu$_{0.07}$TiSe$_2$. Consistent with the development from a semimetal or semiconductor with a very small indirect energy...
Semimetal to semimetal charge density wave transition in 1T-TiSe$_2$ (2007)
Li, G., Hu, W. Z., Qian, D., Hsieh, D., Hasan, M. Z., Morosan, E., ...
We report an infrared study on 1$T$-TiSe$_2$, the parent compound of the newly discovered superconductor Cu$_x$TiSe$_2$. Previous studies of this compound have not conclusively resolved whether it is...
Optical study of the charge-density-wave mechanism in 2$H$-TaS$_2$ and Na$_x$TaS$_2$ (2007)
Hu, W. Z., Li, G., Yan, J., Wen, H. H., Wu, G., Chen, X. H., ...
We report an optical study of transition metal dichalcogenide 2$H$-TaS$_2$ and Na intercalated superconductor Na$_x$TaS$_2$ over a broad frequency range at various temperatures. A clear gap feature...
Tunneling spectroscopy of Tl2Ba2CaCu2O8 single crystals and thin films (2006)
Mazur, Daniel, Zasadzinski, J. F., Gray, K. E., Ma, Y. C., Wang, N. L., Yan, S. L.
Early electron tunneling experiments with the Tl2Ba2CaCu2O8 measured \Delta = 16-28 meV, while bulk optical experiments measured \Delta = 43-45 meV. We report new tunneling measurements of...
Emergence of Fermi pockets in an excitonic CDW melted novel superconductor (2006)
Qian, D., Hsieh, D., Wray, L., Wang, N. L., Morosan, E., Xia, Y., ...
A superconducting (SC) state (Tc ~ 4.2K) has very recently been observed upon successful doping of the CDW ordered triangular lattice TiSe$_2$, with copper. Using high resolution photoemission...
Complete d-Band Dispersion and the Mobile Fermion Scale in NaxCoO2 (2006)
Qian, D., Wray, L., Hsieh, D., Viciu, L., Cava, R. J., Luo, J. L., ...
We utilize fine-tuned polarization selection coupled with excitation-energy variation of photoelectron signal to image the \textit{complete d}-band dispersion relation in sodium cobaltates. A...
Optical study of MgTi$_2$O$_4$: Evidence for an orbital-Peierls state (2006)
Zhou, J., Li, G., Luo, J. L., Ma, Y. C., Wu, Dan, Zhu, B. P., ...
Dimension reduction due to the orbital ordering has recently been proposed to explain the exotic charge, magnetic and structural transitions in some three-dimensional (3D) transitional metal oxides....
Wang, C. H., Chen, X. H., Wu, G., Wu, T., Zhang, H. T., Luo, J. L., ...
Angular-dependent in-plane magnetoresistance (AMR) for single crystal $Na_{0.34}(H_3O)_{0.15}CoO_2$ with charge ordering is studied systematically. The anisotropic magnetoresistance shows a twofold...
Qian, D., Hsieh, D., Wray, L., Fedorov, A., Wu, D., Luo, J. L., ...
We report a state-of-the-art photoemission (ARPES) study of high quality single crystals of the NaxCoO2 series focusing on the fine details of the low-energy states. The Fermi velocity is found to be...
Qian, D., Wray, L., Hsieh, D., Wu, D., Luo, L. J., Wang, N. L., ...
Layered cobaltates embody novel realizations of correlated quantum matter on a spin-1/2 triangular lattice. We report a high-resolution systematic photoemission study of the insulating cobaltates...
Liu, G. T., Luo, J. L., Li, Z., Guo, Y. Q., Wang, N. L., Jin, D., ...
A high quality superconducting Li$_{0.68}$NbO$_2$ polycrystalline sample was synthesized by deintercalation of Li ions from Li$_{0.93}$NbO$_2$. The field dependent resistivity and specific heat were...
Liu, G. T., Luo, J. L., Guo, Y. Q., Su, S. K., Zheng, P., Wang, N. L., ...
A series of in-plane substituted compounds, including Cu-site (SrZn$_x$Cu$_{2-x}$(BO$_3$)$_2$), and B-site (SrCu$_2$(Si$_x$B$_{1-x}$O$_3$)$_2$) substitution, were synthesized by solid state reaction....
Infrared scattering rate of overdoped Tl$_{2}$Ba$_{2}$CuO$_{6+\delta}$ (2005)
We present in-plane optical study on Tl$_{2}$Ba$_{2}$CuO$_{6+\delta}$ single crystals with substantially different $T_c$. The study reveals that the overdoping does not lead to a further increase of...
Optical properties of boron-doped diamond (2005)
Wu, Dan, Ma, Y. C., Wang, Z. L., Luo, Q., Gu, C. Z., Wang, N. L., ...
We report optical reflectivity study on pure and boron-doped diamond films grown by a hot-filament chemical vapor deposition method. The study reveals the formation of an impurity band close to the...
Optical properties of $MgCNi_3$ in the normal state (2005)
Zheng, P., Luo, J. L., Liu, G. T., Zhang, Y. L., Yu, R. C., Jin, C. Q., ...
We present the optical reflectance and conductivity spectra for non-oxide antiperovskite superconductor $MgCNi_{3}$ at different temperatures. The reflectance drops gradually over a large energy...
Angular-dependent Magnetoresistance Oscillations in Na$_{0.48}$CoO$_{2}$ Single Crystal (2005)
Hu, F., Liu, G. T., Luo, J. L., Wu, D., Wang, N. L., Xiang, T.
We report measurements of the c-axis angular-dependent magnetoresistance (AMR) for a Na$_{0.48}$CoO$_{2}$ single crystal, with a magnetic field of 10 T rotating within Co-O planes. Below the...
Single crystals of thallium-based cuprates with the general formula Tl$_{2}$Ba$_{2}$Ca$_{n-1}$Cu$_{n}$O$_{x}$(n=1,2,3) have been grown by the flux method. The superconducting transition temperatures...
Electron-boson mode coupling and the pseudogap of Na$_x$CoO$_2$ by infrared spectroscopy (2005)
Wu, D., Luo, J. L., Wang, N. L.
We report the in-plane optical measurements on Na$_x$CoO$_2$ with 0.18$\leq$x$\leq$0.92. The crystal growth and characterization were described in detail. The spectral weight increases monotonically...
Hysteresis and Anisotropic Magnetoresistance in Antiferromagnetic $Nd_{2-x}Ce_xCuO_{4}$ (2004)
Chen, X. H., Wang, C. H., Wang, G. Y., Luo, X. G., Luo, J. L., Liu, G. T., ...
The out-of-plane resistivity ($\rho_c$) and magnetoresistivity (MR) are studied in antiferromangetic (AF) $Nd_{2-x}Ce_xCuO_{4}$ single crystals, which have three types of noncollinear...
Yang, H. X., Nie, C. J., Shi, Y. G., Yu, H. C., Ding, S., Liu, Y. L., ...
The nonstoichiometric NaxCoO2 system exhibits extraordinary physical properties that correlate with temperature and Na concentration in its layered lattice without evident long-range structure...
Dimensional crossover and anomalous magnetoresistivity in single crystals $Na_xCoO_2$ (2004)
Wang, C. H., Chen, X. H., Luo, J. L., Liu, G. T., Lu, X. X., Zhang, H. T., ...
The in-plane ($\rho_{ab}$) and c-axis ($\rho_c$) resistivities, and the magnetoresistivity of single crystals $Na_xCoO_2$ with x = 0.7, 0.5 and 0.3 were studied systematically. $\rho_{ab}(T)$ shows...
Wang, N. L., Li, G., Wu, Dong, Chen, X. H., Wang, C. H., Ding, H.
We report optical reflectivity study on Nd$_{2-x}$Ce$_x$CuO$_4$ over a broad doping range 0$\leq x\leq$0.20. The study reveals a systematic shift of chemical potential with doping. A pronounced peak...
Doping Effects on the two-dimensional Spin Dimer Compound $SrCu_2(BO_3)_2$ (2004)
Liu, G. T., Luo, J. L., Xiang, T., Wang, N. L., Wu, Z. H., Jing, X. N., ...
A series of compounds M$_{0.1}$Sr$_{0.9}$Cu$_2$(BO$_3$)$_2$ with Sr substituted by M=Al, La, Na and Y were prepared by solid state reaction. XRD analysis showed that these doping compounds are...
Infrared spectroscopy of the charge ordering transition in Na$_{0.5}$CoO$_2$ (2004)
Wang, N. L., Wu, Dong, Li, G., Chen, X. H., Wang, C. H., Luo, X. G.
We report infrared spectra of a Na$_{0.5}$CoO$_2$ single crystal which exhibits a sharp metal-insulator transition near 50 K due to the formation of charge ordering. In comparison with x=0.7 and 0.85...
Optical study on doped polyaniline composite films (2004)
Li, G., Zheng, P., Wang, N. L., Long, Y. Z., Chen, Z. J., Li, J. C., ...
Localization driven by disorder has a strong influence on the conducting property of conducting polymer. A class of authors hold the opinion that disorder in the material is homogeneous and...
Metamagnetic Transition in Na$_{0.85}$CoO$_2$ Single Crystals (2004)
Luo, J. L., Wang, N. L., Liu, G. T., Wu, D., Jing, X. N., Hu, F., ...
We report the magnetization, specific heat and transport measurements of high quality Na$_{0.85}$CoO$_2$ single crystals in applied magnetic fields up to 14T. In high temperatures, the system is in a...
Optical study of the metal-insulator transition in CuIr$_2$S$_4$ crystals (2004)
Wang, N. L., Cao, G. H., Zheng, P., Li, G., Fang, Z., Xiang, T., ...
We present measurements of the optical spectra on single crystals of spinel-type compound \cis. This material undergoes a sharp metal-insulator transition at 230 K. Upon entering the insulating...
Optical properties of pyrochlore oxide $Pb_{2}Ru_{2}O_{7-{\delta}}$ (2003)
Zheng, P., Wang, N. L., Luo, J. L., Jin, R., Mandrus, D.
We present optical conductivity spectra for $Pb_{2}Ru_{2}O_{7-{\delta}}$ single crystal at different temperatures. Among reported pyrochlore ruthenates, this compound exhibits metallic behavior in a...
Infrared probe of the electronic structure and charge dynamics in Na$_{0.7}$CoO$_2$ (2003)
Wang, N. L., Zheng, P., Wu, D., Ma, Y. C., Xiang, T., Jin, R. Y., ...
We present measurements of the optical spectra on Na$_{0.7}$CoO$_2$ single crystals. The optical conductivity shows two broad interband transition peaks at 1.6 eV and 3.2 eV, and a weak midinfrared...
Wang, N. L., Zheng, P., Luo, J. L., Chen, Z. J., Yan, S. L., Fang, L., ...
We report on a study of the in-plane infrared response of a \TBCCO film with $T_c$=108 K. The fingerprint evidence for a strong electron-Boson coupling has been observed. The raw reflectance below...
Marginal Fermi liquid analysis of 300 K reflectance of Bi2Sr2CaCu2O8+x (2003)
Hwang, J., Timusk, T., Puchkov, A. V., Wang, N. L., Gu, G. D., Homes, C. C., ...
We use 300 K reflectance data to investigate the normal-state electrodynamics of the high temperature superconductor Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ over a wide range of doping levels. The...
Infrared properties of La$_{2-x}$(Ca,Sr)$_x$CaCu$_2$O$_{6+\delta}$ single crystals (2002)
Wang, N. L., Zheng, P., Feng, T., Gu, G. D., Homes, C. C., Tranquada, J. M., ...
The in-plane optical properties of two crystals of the bilayer cuprate \LSxCCO, one with excess Ca and $x=0.10$ and the other with Sr and $x=0.15$, were investigated over the frequency range of...
Infrared properties of W-doped charge-density-wave material K$_{0.3}$MoO$_3$ (2002)
Feng, T., Wang, N. L., Zheng, P., Chen, Z. J., Tian, M. L.
The optical conductivity spectra of quasi-one dimensional compounds K$_{0.3}$Mo$_{1-x}$W$_x$O$_3$ (x=0, 0.03 and 0.15) have been studied over broad frequencies. While the dc resistivity measurements...
Wang, N. L., Feng, T., Chen, Z. J., Mori, H.
We performed polarized far-infrared reflectance measurements at different temperatures on $\theta$-ET$_2$RbZn(SCN)$_4$ and $\theta$-ET$_2$CsZn(SCN)$_4$, two typical charge-transfer salts in a series...
Optical evidence for mass enhancement of quasiparticles in pyrochlore Cd$_2$Re$_2$O$_7$ (2002)
Wang, N. L., McGuire, J. J., Timusk, T., Jin, R., He, J., Mandrus, D
We report on the results of optical studies of the newly discovered superconductor Cd$_2$Re$_2$O$_7$ in the normal state. We show that the compound has an exotic metallic state at low temperature....
The oxygen isotope effect in the ab-plane reflectance of underdoped YBa_2Cu_3O_{7-delta} (2002)
Wang, N. L., Timusk, T., Franck, J. P., Schweiss, P., Braden, M., Erb, A.
We have measured the effect of oxygen isotope substitution on the ab-plane reflectance of underdoped YBCO. The frequency shift of the transverse optic phonons due to the substitution of O-16 by O-18...
Oxygen isotope effect in the ab-plane reflectance of underdoped YBa§2Cu§3O§7§-§#d. (2002)
Wang, N.L., Timusk, T., Franck, J.P., Schweiss, P., Braden, M., Erb, A.
Physical Review Letters, 89(2002) S.087003/1-4
Far-infrared study of the insulator-metal transition in $\theta$-(BEDT-TTF)$_2$RbZn(SCN)$_4$ (2001)
Wang, N. L., Mori, H., Tanaka, S., Dong, J., Clayman, B. P.
The temperature-dependent infrared properties of $\theta$-(BEDT-TTF)$_2$RbZn(SCN)$_4$ were investigated. In the temperatures above the metal-insulator (M-I) transition, the optical conductivity...
On the 590cm-1 B1g feature in underdoped Bi2Sr2CaCu2O8+delta (1999)
Hewitt, Kevin C., Wang, N. L., Irwin, J. C., Pooke, D. M., Pantoja, A. E., Trodahl, H. J.
Raman scattering studies have been performed on underdoped Bi2Sr2CaCu2O8+delta. In single crystals underdoped by oxygen removal, a 590 cm-1 peak is observed in the B1g spectrum. The feature is...
Ando, Yoichi, Boebinger, G. S., Passner, A., Wang, N. L., Geibel, C., Steglich, F., ...
The normal-state Hall coefficient R_H and the in-plane resistivity \rho_{ab} are measured in La-doped Bi_{2}Sr_{2}CuO_{y} (T_c \simeq 13 K) single crystals and La_{2-x}Sr_{x}CuO_{4} thin films by...