Now showing items 1-19 of 19

    • Anisotropic neutron spin resonance in underdoped superconducting NaFe1−xCoxAs 

      Zhang, Chenglin; Song, Yu; Regnault, L.-P.; Su, Yixi; Enderle, M.; Kulda, J.; Tan, Guotai; Sims, Zachary C.; Egami, Takeshi; Si, Qimiao; Dai, Pengcheng (2014)
      We use polarized inelastic neutron scattering (INS) to study spin excitations in superconducting NaFe0.985Co0.015As (C15) with static antiferromagnetic (AF) order along the a axis of the orthorhombic structure and ...
    • Critical quadrupole fluctuations and collective modes in iron pnictide superconductors 

      Thorsmølle, V.K.; Khodas, M.; Yin, Z.P.; Zhang, Chenglin; Carr, S.V.; Dai, Pengcheng; Blumberg, G. (2016)
      The multiband nature of iron pnictides gives rise to a rich temperature-doping phase diagram of competing orders and a plethora of collective phenomena. At low dopings, the tetragonal-to-orthorhombic structural transition ...
    • Effect of Pnictogen Height on Spin Waves in Iron Pnictides 

      Zhang, Chenglin; Harriger, Leland W.; Yin, Zhiping; Lv, Weicheng; Wang, Miaoyin; Tan, Guotai; Song, Yu; Abernathy, D.L.; Tian, Wei; Egami, Takeshi; Haule, Kristjan; Kotliar, Gabriel; Dai, Pengcheng (2014)
      We use inelastic neutron scattering to study spin waves in the antiferromagnetic ordered phase of iron pnictide NaFeAs throughout the Brillouin zone. Comparing with the well-studied AFe2As2 (A=Ca, Sr, Ba) family, spin waves ...
    • Electron doping evolution of structural and antiferromagnetic phase transitions in NaFe1−xCoxAs iron pnictides 

      Tan, Guotai; Song, Yu; Zhang, Chenglin; Lin, Lifang; Xu, Zhuang; Hou, Tingting; Tian, Wei; Cao, Huibo; Li, Shiliang; Feng, Shiping; Dai, Pengcheng (2016)
      We use transport and neutron diffraction to study the electronic phase diagram of NaFe1−xCoxAs. In the undoped state, NaFeAs exhibits a tetragonal-to-orthorhombic structural transition below Tsfollowed by a collinear ...
    • Electron doping evolution of the magnetic excitations in NaFe1−xCoxAs 

      Carr, Scott V.; Zhang, Chenglin; Song, Yu; Tan, Guotai; Li, Yu; Abernathy, D.L.; Stone, M.B.; Granroth, G.E.; Perring, T.G.; Dai, Pengcheng (2016)
      We use time-of-flight (TOF) inelastic-neutron-scattering (INS) spectroscopy to investigate the doping dependence of magnetic excitations across the phase diagram of NaFe 1 − x Co x As with x = 0 , 0.0175, ...
    • Electron doping evolution of the neutron spin resonance in NaFe1−xCoxAs 

      Zhang, Chenglin; Lv, Weicheng; Tan, Guotai; Song, Yu; Carr, Scott V.; Chi, Songxue; Matsuda, M.; Christianson, A.D.; Fernandez-Baca, J.A.; Harriger, L.W.; Dai, Pengcheng (2016)
      Neutron spin resonance, a collective magnetic excitation coupled to superconductivity, is one of the most prominent features shared by a broad family of unconventional superconductors including copper oxides, iron pnictides, ...
    • Evolution of London penetration depth with scattering in single crystals of K1−xNaxFe2As2 

      Kim, H.; Tanatar, M.A.; Liu, Yong; Sims, Zachary Cole; Zhang, Chenglin; Dai, Pengcheng; Lograsso, T.A.; Prozorov, R. (2014)
      London penetration depth, λ(T), was measured in single crystals of K1−xNaxFe2As2, x=0 and 0.07, down to temperatures of 50 mK, ∼Tc/50. Isovalent substitution of Na for K significantly increases impurity scattering, ...
    • Influence of doping on the spin dynamics and magnetoelectric effect in hexagonalᅠY0.7Lu0.3MnO3 

      Tian, W.; Tan, Guotai; Liu, Liu; Zhang, Jinxing; Winn, Barry; Hong, Tao; Fernandez-Baca, J.A.; Zhang, Chenglin; Dai, Pengcheng (2014)
      We use inelastic neutron scattering and dielectric constant measurements to study the doping influence on the spin dynamics and magnetoelectric (ME) effect in hexagonalY0.7Lu0.3MnO3. In undoped YMnO3 and LuMnO3, the Mn ...
    • Magnetic moment evolution and spin freezing in doped BaFe2As2 

      Pelliciari, Jonathan; Huang, Yaobo; Ishii, Kenji; Zhang, Chenglin; Dai, Pengcheng; Chen, Gen Fu; Xing, Lingyi; Wang, Xiancheng; Jin, Changqing; Ding, Hong; Werner, Philipp; Schmitt, Thorsten (2017)
      Fe-K β X-ray emission spectroscopy measurements reveal an asymmetric doping dependence of the magnetic moments μbare in electron- and hole-doped BaFe2As2. At low temperature, μbare is nearly constant in hole-doped samples, ...
    • A Mott insulator continuously connected to iron pnictide superconductors 

      Song, Yu; Yamani, Zahra; Cao, Chongde; Li, Yu; Zhang, Chenglin; Chen, Justin S.; Huang, Qingzhen; Wu, Hui; Tao, Jing; Zhu, Yimei; Tian, Wei; Chi, Songxue; Cao, Huibo; Huang, Yao-Bo; Dantz, Marcus; Schmitt, Thorsten; Yu, Rong; Nevidomskyy, Andriy H.; Morosan, Emilia; Si, Qimiao; Dai, Pengcheng (2016)
      Iron-based superconductivity develops near an antiferromagnetic order and out of a bad-metal normal state, which has been interpreted as originating from a proximate Mott transition. Whether an actual Mott insulator can ...
    • Neutron spin resonance as a probe of superconducting gap anisotropy in partially detwinned electron underdoped NaFe0.985Co0.015As 

      Zhang, Chenglin; Park, J.T.; Lu, Xingye; Yu, Rong; Li, Yu; Zhang, Wenliang; Zhao, Yang; Lynn, J.W.; Si, Qimiao; Dai, Pengcheng (2015)
      We use inelastic neutron scattering (INS) to study the spin excitations in partially detwinned NaFe0.985Co0.015As which has coexisting static antiferromagnetic (AF) order and superconductivity (Tc=15 K, TN=30 K). In previous ...
    • Orbital Selective Spin Excitations and their Impact on Superconductivity of LiFe1−xCoxAs 

      Li, Yu; Yin, Zhiping; Wang, Xiancheng; Tam, David W.; Abernathy, D.L.; Podlesnyak, A.; Zhang, Chenglin; Wang, Meng; Xing, Lingyi; Jin, Changqing; Haule, Kristjan; Kotliar, Gabriel; Maier, Thomas A.; Dai, Pengcheng (2016)
      We use neutron scattering to study spin excitations in single crystals of LiFe0.88Co0.12As, which is located near the boundary of the superconducting phase of LiFe1−xCoxAs and exhibits non-Fermi-liquid behavior indicative ...
    • Phase separation, competition, and volume-fraction control in NaFe1−xCoxA 

      Ma, Long; Dai, J.; Wang, P.S.; Lu, R.; Song, Yu; Zhang, Chenglin; Tan, G.T.; Dai, Pengcheng; Hu, D.; Li, S.L.; Normand, B.; Yu, Weiqiang (2014)
      We report a detailed nuclear magnetic resonance (NMR) study by combined Na23 and As75 measurements over a broad range of doping to map the phase diagram of NaFe1−xCoxAs. In the underdoped regime (x≤0.017), we find a magnetic ...
    • Short-range cluster spin glass near optimal superconductivity in BaFe2−xNixAs2 

      Lu, Xingye; Tam, David W.; Zhang, Chenglin; Luo, Huiqian; Wang, Meng; Zhang, Rui; Harriger, Leland W.; Keller, T.; Keimer, B.; Regnault, L.-P.; Maier, Thomas A.; Dai, Pengcheng (2014)
      High-temperature superconductivity in iron pnictides occurs when electrons are doped into their antiferromagnetic (AF) parent compounds. In addition to inducing superconductivity, electron doping also changes the static ...
    • Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba0:67K0:33Fe2As2 

      Song, Yu; Man, Haoran; Zhang, Rui; Lu, Xingye; Zhang, Chenglin; Wang, Meng; Tan, Guotai; Regnault, L.-P.; Su, Yixi; Kang, Jian; Fernandes, Rafael M.; Dai, Pengcheng (2016)
      We use polarized inelastic neutron scattering to study the temperature and energy dependence of spin space anisotropies in the optimally-hole-doped iron pnictide Ba0.67K0.33Fe2As2 (Tc=38 K). In the superconducting state, ...
    • Superconductivity and antiferromagnetism in Ba0.75K0.25Fe2As2 single crystals as seen by 57Fe Mossbauer spectroscopy 

      Munevar, J.; Micklitz, H.; Aguero, J.; Tan, Guotai; Zhang, Chenglin; Dai, Pengcheng; Baggio-Saitovitch, E. (2013)
    • Superconductivity and electronic fluctuations in Ba1−xKxFe2As2 studied by Raman scattering 

      Wu, S.-F.; Richard, P.; Ding, H.; Wen, H.-H.; Tan, Guotai; Wang, Meng; Zhang, Chenglin; Dai, Pengcheng; Blumberg, G. (2017)
      Using polarization-resolved electronic Raman scattering we study underdoped, optimally doped, and overdoped Ba1−xKxFe2As2 samples in the normal and superconducting states. We show that low-energy nematic fluctuations are ...
    • Temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe0.9785Co0.0215As 

      Song, Yu; Wang, Weiyi; Zhang, Chenglin; Gu, Yanhong; Lu, Xingye; Tan, Guotai; Su, Yixi; Bourdarot, Frédéric; Christianson, A.D.; Li, Shiliang; Dai, Pengcheng (2017)
      We use unpolarized and polarized neutron scattering to study the temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe0.9785Co0.0215As, with coexisting superconductivi ...
    • Two-Dimensional Massless Dirac Fermions in Antiferromagnetic AFe2As2 (A=Ba,Sr) 

      Chen, Zhi-Guo; Wang, Luyang; Song, Yu; Lu, Xingye; Luo, Huiqian; Zhang, Chenglin; Dai, Pengcheng; Yin, Zhiping; Haule, Kristjan; Kotliar, Gabriel (2017)
      We report infrared studies of AFe2As2 (A=Ba, Sr), two representative parent compounds of iron-arsenide superconductors, at magnetic fields (B) up to 17.5 T. Optical transitions between Landau levels (LLs) were observed in ...