Wang, X. F., Wu, T., Wu, G., Liu, R. H., Chen, H., Xie, Y. L., ...
We study systematically transport, susceptibility and heat capacity for BaFe$_{2-x}$Co$_x$As$_2$ single crystals. In the underdoped region, spin density wave (SDW) transition is observed in both...
Wu, T., Ying, J. J., Wu, G., Liu, R. H., He, Y., Chen, H., ...
The temperature dependence of electron spin resonance (ESR) was studied in the oxypnictide superconductors LaFeAsO$_{1-x}$F$_x$ (x = 0.0 and 0.13). In the samples, the ESR signal indicates that the g...
Liu, R. H., Wu, G., Chen, H., Xie, Y. L., Yan, Y. J., Wu, T., ...
We prepared the samples K$_{1-x}$Ln$_{x}$Fe$_2$As$_2$ (Ln=Sm, Nd and La) with ThCr$_2$Si$_2$-type structure. These samples were characterized by X-ray diffraction, resistivity, susceptibility and...
Baker, P. J., Giblin, S. R., Pratt, F. L., Liu, R. H., Wu, G., Chen, X. H., ...
We report heat capacity measurements of the pnictide materials SmFeAsO$_{1-x}$F$_x$, NdFeAsO, LaFeAsO$_{1-x}$F$_x$ and LiFeAs. For SmFeAsO$_{1-x}$F$_x$, with x close to 0.1, we use 3 He measurements...
Dubroka, Adam, Kim, Kyung Wan, Rössle, Matthias, Malik, V. K., Drew, Alan J., Liu, R. H., ...
We present far-infrared ellipsometric measurements of polycrystalline samples of the pnictide superconductor RFeAsO0.82F0.18 (R=Nd and Sm). We find evidence that the electronic properties are...
Dubroka, Adam, Kim, Kyung Wan, Rössle, Matthias, Malik, V. K., Drew, Alan J., Liu, R. H., ...
We present far-infrared ellipsometric measurements of polycrystalline samples of the pnictide superconductor RFeAsO0.82F0.18 (R=Nd and Sm). We find evidence that the electronic properties are...
Drew, Alan J., Pratt, F. L., Lancaster, T., Blundell, S. J., Baker, P. J., Liu, R. H., ...
Muon spin rotation experiments were performed on the pnictide high temperature superconductor SmFeAsO1-xFx with x=0.18 and 0.3. We observed an unusual enhancement of slow spin fluctuations in the...
Drew, Alan J., Pratt, F. L., Lancaster, T., Blundell, S. J., Baker, P. J., Liu, R. H., ...
Muon spin rotation experiments were performed on the pnictide high temperature superconductor SmFeAsO1-xFx with x=0.18 and 0.3. We observed an unusual enhancement of slow spin fluctuations in the...
Superconductivity at 56 K in Samarium-doped SrFeAsF (2008)
Wu, G., Xie, Y. L., Chen, H., Zhong, M., Liu, R. H., Shi, B. C., ...
Here we report discovery of superconductivity at 56 K in nonminal composition $Sr_{1-x}Sm_xFeAsF$ (x=0.5) with ZrCuSiAs-type structure. The $T_c$ is almost the same as the highest superconducting...
Liu, R. H., Wu, T., Wu, G., Chen, H., Wang, X. F., Xie, Y. L., ...
We have studied the effect of isotopic substitution on the superconducting $T_c$ and spin-density wave $T_{SDW}$ in the $SmFeAsO_{1-x}F_x$ by replacing $^{16}O$ with the isotope $^{18}O$, and...
Yin, Yi, Zech, M., Williams, T. L., Wang, X. F., Wu, G., Chen, X. H., ...
High temperature superconductors, materials which conduct electricity without energy loss at practically attainable temperatures, have resisted most attempts at explanation and application for over...
Balicas, L., Gurevich, A., Jo, Y. J., Jaroszynski, J., Larbalestier, D. C., Liu, R. H., ...
To probe manifestations of multiband superconductivity in oxypnictides, we measured the angular dependence of magnetic torque $\tau(\theta)$ in the mixed state of SmO$_{0.8}$F$_{0.2}$FeAs single...
Doping-Driven Collapse of the SDW Correlation Gap in SmFeAsO$_{1-x}$F$_{x}$ (2008)
Riggs, Scott C., McDonald, R. D., Kemper, J. B., Stegen, Z., Boebinger, G. S., Balakirev, F. F., ...
We report the Hall resistivity, $\rho_{xy}$ of polycrystalline SmFeAsO$_{1-x}$F$_{x}$ for four different fluorine concentrations from the onset of superconductivity through the collapse of the...
Rearrangement of Sodium ordering and its effect on physical properties in $Na_xCoO_2$ system (2008)
Wu, T., Liu, K., Chen, H., Wu, G., Luo, Q. L., Ying, J. J., ...
We systematically study Raman spectroscopy of cleaved Na$_x$CoO$_2$ single crystals with 0.37 $\leq$ x $\leq$ 0.80. The Raman shift of A$_{1g}$ mode is found to be linearly dependent on Na content,...
Zhang, Y., Wei, J., Ou, H. W., Zhao, J. F., Zhou, B., Chen, F., ...
The nature of spin-density wave and its relation with superconductivity are crucial issues in the newly discovered Fe-based high temperature superconductors. Particularly it is unclear whether the...
Magnetic phase diagram in Eu$_{1-x}$La$_x$Fe$_2$As$_2$ single crystals (2008)
Wu, T., Wu, G., Chen, H., Xie, Y. L., Liu, R. H., Wang, X. F., ...
We have systematically measured resistivity, susceptibility and specific heat under different magnetic fields (H) in Eu$_{1-x}$La$_x$Fe$_2$As$_2$ single crystals. It is found that a metamagnetic...
Drew, A. J., Niedermayer, Ch., Baker, P. J., Pratt, F. L., Blundell, S. J., Lancaster, T., ...
The recent observation of superconductivity with critical temperatures up to 55 K in the FeAs based pnictide compounds marks the first discovery of a non copper-oxide based layered high-Tc...
Coexistence of the spin-density-wave and superconductivity in the (Ba,K)Fe2As2 (2008)
Chen, H., Ren, Y., Qiu, Y., Bao, Wei, Liu, R. H., Wu, G., ...
The relation between the spin-density-wave (SDW) and superconducting order is a central topic in current research on the FeAs-based high Tc superconductors. Conflicting results exist in the...
Wu, G., Chen, H., Wu, T., Xie, Y. L., Yan, Y. J., Liu, R. H., ...
We report that intrinsic transport and magnetic properties, and their anisotropy from high quality single crystal $CaFe_2As_2$. The resistivity anisotropy ($\rho_c/\rho_{ab}$) is $\sim 50 $, and less...
Margadonna, Serena, Takabayashi, Yasuhiro, McDonald, Martin T., Brunelli, Michela, Wu, G., Liu, R. H., ...
The fluorine-doped rare-earth iron oxyarsenides, REFeAsO1-xFx (RE =rare earth) have recently emerged as a new family of high-temperature superconductors with transition temperatures (Tc) as high as...
Riggs, S. C., Kemper, J. B., Jo, Y., Stegen, Z., Balicas, L., Boebinger, G. S., ...
We report the resistivity of a series of fluorine-doped SmFeAsO1-xFx polycrystalline superconductors in magnetic fields up to 60T. For underdoped samples (x < 0.15), the low temperature resistive...
Thermodynamic properties of Ba1-xMxFe2As2 (M = La and K) (2008)
Dong, J. K., Ding, L., Wang, H., Wang, X. F., Wu, T., Chen, X. H., ...
The specific heat $C(T)$ of BaFe$_2$As$_2$ single crystal, electron-doped Ba$_{0.7}$La$_{0.3}$Fe$_2$As$_2$ and hole-doped Ba$_{0.5}$K$_{0.5}$Fe$_2$As$_2$ polycrystals were measured. For undoped...
Huang, Q., Qiu, Y., Bao, Wei, Lynn, J. W., Green, M. A., Chen, Y., ...
In addition to higher Tc compared with the ubiquitous cuprates for a material composed of a single electronically active layer, the newly discovered LnFeAsO superconductors offer additional...
Yang, L. X., Zhang, Y., Ou, H. W., Zhao, J. F., Shen, D. W., Zhou, B., ...
The magnetic properties in the parent compounds are often intimately related to the microscopic mechanism of superconductivity. Here we report the first direct measurements on the electronic...
Wang, X. F., Wu, T., Wu, G., Chen, H., Xie, Y. L., Ying, J. J., ...
Sizable single crystals of $BaFe_2As_2$ have been grown with self-flux method. The crystals are plate-like with c-axis perpendicular to the plane. The size can be as large as 3 x 5 x 0.2 $mm^3$. The...
Structure and Magnetic Order in the NdFeAs(O,F) Superconductor System (2008)
Qiu, Y., Bao, Wei, Huang, Q., Yildirim, T., Simmons, J., Lynn, J. W., ...
The transition temperature Tc~26 K of the recently discovered superconductor LaFeAs(O,F) has been demonstrated to be extremely sensitive to the lanthanide ion, reaching 55 K for the Sm containing...
Far-infrared probe of superconductivity in SmO$_{1-x}$F$_{x}$FeAs} (2008)
Mirzaei, S. I., Guritanu, V., Kuzmenko, A. B., Senatore, C., Wu, G., ...
We report far-infrared reflectance measurements on polycrystalline superconducting samples of SmO$_{1-x}$F$_{x}$FeAs ($x$ = 0.12, 0.15 and 0.2). We clearly observe superconductivity induced changes...
Superconductivity induced by oxygen deficiency in Sr-doped LaOFeAs (2008)
Wu, G., Chen, H., Xie, Y. L., Yan, Y. J., Wu, T., Liu, R. H., ...
We synthesized Sr-doped $La_{0.85}Sr_{0.15}OFeAs$ sample with single phase, and systematically studied the effect of oxygen deficiency in the Sr-doped LaOFeAs system. It is found that substitution of...
Wu, G., Liu, R. H., Chen, H., Yan, Y. J., Wu, T., Xie, Y. L., ...
We synthesized the samples $Ba_{1-x}M_xFe_2As_2$ (M=La and K) with $ThCr_2Si_2$-type structure. These samples were systematically characterized by resistivity, thermoelectic power (TEP) and Hall...
Ou, H. W., Zhao, J. F., Zhang, Y., Xie, B. P., Shen, D. W., Zhu, Y., ...
The misfit oxide, Bi$_{2}$Ba$_{1.3}$K$_{0.6}$Co$_{2.1}$O$_{y}$, made of alternating rocksalt-structured [BiO/BaO] layers and hexagonal CoO$_{2}$ layers, was studied by angle-resolved photoemission...
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...
Ou, H. W., Zhang, Y., Zhao, J. F., Wei, J., Shen, D. W., Zhou, B., ...
We investigated the temperature dependence of the density-of-states in the iron-based superconductor SmO_1-xF_xFeAs (x=0, 0.12, 0.15, 0.2) with high resolution angle-integrated photoemission...
The BCS-like gap in superconductor SmFeAsO_0.85F_0.15 (2008)
Chen, T. Y., Tesanovic, Z., Liu, R. H., Chen, X. H., Chien, C. L.
Since the discovery of superconductivity in the cuprates two decades ago, it has been firmly established that the CuO_2 plane is consequential for high T_C superconductivity and a host of other very...
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...
Senatore, C., Cantoni, M., Wu, G., Liu, R. H., Chen, X. H., Flukiger, R.
We report specific heat measurements at magnetic fields up to 20 T on the recently discovered superconductor SmFeAsO$_{0.85}$F$_{0.15}$. The B-T diagram of a polycrystalline...
Dubroka, A., Kim, K. W., Roessle, M., Malik, V. K., Liu, R. H., Wu, G., ...
We present ellipsometric measurements of the far-infrared dielectric response of polycrystalline samples of the new pnictide superconductor RO0.82F0.18FeAs (R=Nd and Sm). We find evidence that the...
Drew, A. J., Pratt, F. L., Lancaster, T., Blundell, S. J., Baker, P. J., Liu, R. H., ...
Muon-spin rotation experiments were performed on the pnictide high temperature superconductor SmFeAsO$_{1-x}$F$_{x}$ with x=0.18 and 0.3. We observed an unusual enhancement of slow spin fluctuations...
Neutron scattering study of the oxypnictide superconductor La(O,F)FeAs (2008)
Qiu, Y., Kofu, M., Bao, Wei, Huang, Q., Yildirim, T., ...
The newly discovered superconductor La(O,F)FeAs (Tc = 26 K) was investigated using the neutron scattering technique. No spin-density-wave (SDW) order was observed in the normal state nor in the...
X-ray spectra and electronic structure of FeAs superconductors (2008)
Kurmaev, E. Z., Wilks, R. G., Moewes, A., Skorikov, N. A., Izyumov, Yu. A., Finkelstein, L. D., ...
The densities of the valence and conduction band electronic states of the newly discovered layered superconductors LaOFeAs, LaO$_{0.87}$F$_{0.13}$FeAs (Tc=26 K), SmO$_{0.95}$F$_{0.05}$FeAs and...
Specific heat of the iron-based high-$T_c$ superconductor SmO$_{1-x}$F$_x$FeAs (2008)
Ding, L., He, C., Dong, J. K., Wu, T., Liu, R. H., Chen, X. H., ...
The specific heat $C(T)$ of new iron-based high-$T_c$ superconductor SmO$_{1-x}$F$_x$FeAs ($0 \leq x \leq 0.2$) was systematically studied. For undoped $x$ = 0 sample, a specific heat jump was...
Liu, R. H., Wu, G., Wu, T., Fang, D. F., Chen, H., Li, S. Y., ...
The magnetic fluctuations associated with a quantum critical point (QCP) are widely believed to cause the non-Fermi liquid behaviors and unconventional superconductivities, for example, in heavy...
Lorenz, B., Sasmal, K., Chaudhury, R. P., Chen, X. H., Liu, R. H., Wu, T., ...
High temperature superconductors with a Tc above 40 K have been found to be strongly correlated electron systems and to have a layered structure. Guided by these rules, Kamihara et al. discovered a...
Angle integrated photoemission study of SmO$_{0.85}$F$_{0.15}$FeAs (2008)
Ou, H. W., Zhao, J. F., Zhang, Y., Shen, D. W., Zhou, B., Yang, L. X., ...
The electronic structure of the new superconductor, SmO$_{1-x}$F$_x$FeAs ($x=0.15$), has been studied by angle-integrated photoemission spectroscopy. Our data show a sharp feature very close to the...
Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAsO_{1-x}F_x$ (2008)
Chen, X. H., Wu, T., Wu, G., Liu, R. H., Chen, H., Fang, D. F.
Since the discovery of high-transition temperature ($T_c$) superconductivity in layered copper oxides, extensive efforts have been devoted to explore the higher $T_c$ superconductivity. However, the...
Low-temperature phonon thermal conductivity of cuprate single crystals (2007)
Li, S. Y., Payeur, A., Fournier, P., Wang, C. H., Chen, X. H., ...
The effect of sample size and surface roughness on the phonon thermal conductivity $\kappa_p$ of Nd$_2$CuO$_4$ single crystals was studied down to 50 mK. At 0.5 K, $\kappa_p$ is proportional to...
Luo, X. G., Chen, H., Wang, G. Y., Wu, G., Wu, T., Zhao, L., ...
Resistivity under magnetic field, thermopower and Hall coefficient are systematically studied for [Bi$_2$Ba$_{1.3}$K$_{0.6}$Co$_{0.1}$]$^{RS}$[CoO$_2$]$_{1.97}$ single crystal. In-plane resistivity...
Intergrowth and thermoelectric properties in the Bi-Ca-Co-O system (2007)
Luo, X. G., Jing, Y. C., Chen, H., Chen, X. H.
Single crystals of the Bi-Ca-Co-O system have been grown using the flux method with cooling from 900$\celsius$ and 950$\celsius$, respectively. The single crystals are characterized by transmission...
Chen, X. H., Wu, T., Wang, C. H., Wu, G., Fang, D. F., Luo, J. L., ...
We study anisotropic magnetoresistance (MR) and magnetization with rotating magnetic field (B) within CuO_2 plane in lightly doped AF Nd_{2-x}Ce_xCuO_{4}. \emph{A giant anisotropy} in MR is observed,...
Origin of superconductivity in nominally "undoped" T'-La$_{2-x}$Y$_{x}$CuO$_{4}$ films (2007)
Zhao, L., Liu, R. H., Wu, G., Wang, G. Y., Wu, T., Luo, X. G., ...
We have systematically studied the transport properties of the La$_{2-x}$Y$_{x}$CuO$_{4}$(LYCO) films of T'-phase ($0.05\leq x \leq 0.30$). In this nominally "undoped" system, superconductivity was...
Magnetic field induced spin-flop transition in Na$_x$CoO$_2$ (0.5$ (2007)
Wu, T., Fang, D. F., Wang, G. Y., Zhao, L., Wu, G., Luo, X. G., ...
The isothermal magnetoresistance (MR) with magnetic field (H) parallel to and perpendicular to ab plane is systematically studied on the single crystal Na$_{0.52}$CoO$_2$ with charge ordering at...
Transport properties in Cu$_{x}$TiSe$_{2}$ (0.015$\leq$x$\leq$0.110) Single Crystal (2007)
Wu, G., Yang, H. X., Zhao, L., Luo, X. G., Wu, T., Wang, G. Y., ...
Transport properties are systematically studied for the single crystals Cu$_{x}$TiSe$_{2}$ (0.015$\leq$x$\leq$0.110). Both of in-plane and out-of-plane resistivity show the coexistence of...
Novel dynamical effects and glassy response in strongly correlated electronic system (2007)
Wang, G. Y., Chen, X. H., Wu, T., Luo, X. G., Zhang, W. T., Wu, G.
We find an unconventional nucleation of low temperature paramagnetic metal (PMM) phase with monoclinic structure from the matrix of high-temperature antiferromagnetic insulator (AFI) phase with...
Wang, G. Y., Zhang, J. D., Yang, R. L., Chen, X. H.
The oxygen isotope effect on the superconductivity, stripe phase and structure transition is systematically investigated in La$_{1.6-x}$Nd$_{0.4}$Sr$_{x}$CuO$_4$ with static stripe phase....
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...
Single-gap s-wave superconductivity in Cu$_x$TiSe$_2$ (2007)
Li, S. Y., Taillefer, Louis, Wu, G., Chen, X. H.
The in-plane thermal conductivity $\kappa$ of the layered superconductor Cu$_x$TiSe$_2$ was measured down to temperatures as low as $T_c$/40, at $x$ = 0.06 near where the CDW order vanishes. The...
Evolution of the Electronic Structure of 1T-CuxTiSe2 (2006)
Zhao, J. F., Ou, H. W., Wu, G., Xie, B. P., Zhang, Y., Shen, D. W., ...
The electronic structure of a new charge-density-wave/ superconductor system, 1T-CuxTiSe2, has been studied by photoemission spectroscopy. A correlated semiconductor band structure is revealed for...
Zhao, L., Wu, G., Liu, R. H., Chen, X. H.
The superconducting nominal "non-doped" $La_{1.85}Y_{0.15}CuO_4$ (LYCO) thin films are successfully prepared by dc magnetron-sputtering and in situ post-annealing in vacuum. The best $T_{C0}$ more...
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...