Browsing Physics and Astronomy by Author "Si, Qimiao"
Now showing items 118 of 18

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 ... 
Antiferroquadrupolar and IsingNematic Orders of a Frustrated BilinearBiquadratic Heisenberg Model and Implications for the Magnetism of FeSe
Yu, Rong; Si, Qimiao (2015)Motivated by the properties of the iron chalcogenides, we study the phase diagram of a generalized Heisenberg model with frustrated bilinearbiquadratic interactions on a square lattice. We identify zerotemperature phases ... 
Cluster extended dynamical meanfield approach and unconventional superconductivity
Pixley, J.H.; Cai, Ang; Si, Qimiao (2015)The extended dynamical meanfield theory has played an important role in the study of quantum phase transitions in heavyfermion systems. In order to incorporate the physics of unconventional superconductivity, we develop ... 
Cluster extended dynamical meanfield approach and unconventional superconductivity
Pixley, J.H.; Cai, Ang; Si, Qimiao (2015)The extended dynamical meanfield theory has played an important role in the study of quantum phase transitions in heavyfermion systems. In order to incorporate the physics of unconventional superconductivity, we develop ... 
Electron Correlation and Spin Dynamics in Iron Pnictides and Chalcogenides
Yu, Rong; Si, Qimiao; Goswami, Pallab; Abrahams, Elihu (2012) 
Electronic nematic correlations in the stressfree tetragonal state of BaFe2−xNixAs2
Man, Haoran; Lu, Xingye; Chen, Justin S.; Zhang, Rui; Zhang, Wenliang; Luo, Huiqian; Kulda, J.; Ivanov, A.; Keller, T.; Morosan, Emilia; Si, Qimiao; Dai, Pengcheng (2015)We use transport and neutron scattering to study electronic, structural, and magnetic properties of the electrondoped BaFe2−xNixAs2 iron pnictides in uniaxialstrained and externalstressfree detwinned states. Using a ... 
Energy dependence of the spin excitation anisotropy in uniaxialstrained BaFe1.9Ni0.1As2
Song, Yu; Lu, Xingye; Abernathy, D.L.; Tam, David W.; Niedziela, J.L.; Tian, Wei; Luo, Huiqian; Si, Qimiao; Dai, Pengcheng (2015)We use inelastic neutron scattering to study the temperature and energy dependence of the spin excitation anisotropy in uniaxialstrained electrondoped iron pnictide BaFe1.9Ni0.1As2 near optimal superconductivity (Tc=20K). ... 
Fieldinduced longrange magnetic order in the spinsinglet groundstate system YbAl3C3: Neutron diffraction study
Khalyavin, D.D.; Adroja, D.T.; Manuel, P.; DaoudAladine, A.; Kosaka, M.; Kondo, K.; McEwen, K.A.; Pixley, J.H.; Si, Qimiao (2013)The 4felectron system YbAl3C3 with a nonmagnetic spindimer ground state has been studied by neutron diffraction in an applied magnetic field. A longrange magnetic order involving both ferromagnetic and antiferromagnetic ... 
Glide reflection symmetry, Brillouin zone folding, and superconducting pairing for the P4/nmm space group
Nica, Emilian M.; Yu, Rong; Si, Qimiao (2015)Motivated by the studies of the superconducting pairing states in the ironbased superconductors, we analyze the effects of Brillouin zone folding procedure from a spacegroup symmetry perspective for a general class of ... 
Heavyfermion quantum criticality and destruction of the Kondo effect in a nickelﾠoxypnictide
Luo, Yongkang; Pourovskii, Leonid; Rowley, S.E.; Li, Yuke; Feng, Chunmu; Georges, Antoine; Dai, Jianhui; Cao, Guanghan; Xu, Zhuﾒan; Si, Qimiao; Ong, N.P. (2014)A quantum critical point arises at a continuous transformation between distinct phases of matter at zero temperature. Studies in antiferromagnetic heavyfermion materials have revealed that quantum criticality has several ... 
Kondo Destruction and Valence Fluctuations in an Anderson Model
Pixley, J.H.; Kirchner, Stefan; Ingersent, Kevin; Si, Qimiao (2012)Unconventional quantum criticality in heavyfermion systems has been extensively analyzed in terms of a critical destruction of the Kondo effect. Motivated by a recent demonstration of quantum criticality in a mixedvalent ... 
Magnetic and Ising quantum phase transitions in a model for isoelectronically tuned iron pnictides
Wu, Jianda; Si, Qimiao; Abrahams, Elihu (2016)Considerations of the observed badmetal behavior in Febased superconductors led to an early proposal for quantum criticality induced by isoelectronic P for As doping in iron arsenides, which has since been experimentally ... 
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 ... 
OrbitalSelective Mott Phase in Multiorbital Models for Alkaline Iron Selenides K1−xFe2−ySe2
Yu, Rong; Si, Qimiao (2013)We study a multiorbital model for the alkaline iron selenides K1−xFe2−ySe2 using a slavespin method. With or without ordered vacancies, we identify a metaltoMottinsulator transition at the commensurate filling of six ... 
Pairing correlations near a Kondodestruction quantum critical point
Pixley, J.H.; Deng, Lili; Ingersent, Kevin; Si, Qimiao (2015)Motivated by the unconventional superconductivity observed in heavyfermion metals, we investigate pairing susceptibilities near a continuous quantum phase transition of the Kondodestruction type. We solve twoimpurity ... 
Pairing correlations near a Kondodestruction quantum critical point
Pixley, J.H.; Deng, Lili; Ingersent, Kevin; Si, Qimiao (2015)Motivated by the unconventional superconductivity observed in heavyfermion metals, we investigate pairing susceptibilities near a continuous quantum phase transition of the Kondodestruction type. We solve twoimpurity ... 
Spin dynamics of a J1 J2K model for the paramagnetic phase of iron pnictides
Yu, Rong; Wang, Zhentao; Goswami, Pallab; Nevidomskyy, Andriy H.; Si, Qimiao; Abrahams, Elihu (2012)We study the finitetemperature spin dynamics of the paramagnetic phase of iron pnictides within an antiferromagnetic J1J2 Heisenberg model on a square lattice with a biquadratic coupling −K(Si · Sj )2 between the ... 
StrainDriven Approach to Quantum Criticality in AFe2As2 with A=K, Rb, and Cs
Eilers, Felix; Grube, Kai; Zocco, Diego A.; Wolf, Thomas; Merz, Michael; Schweiss, Peter; Heid, Rolf; Eder, Robert; Yu, Rong; Zhu, JianXin; Si, Qimiao; Shibauchi, Takasada; Löhneysen, Hilbert v. (2016)The ironbased superconductors AFe2As2 with A=K, Rb, Cs exhibit large Sommerfeld coefficients approaching those of heavyfermion systems. We have investigated the magnetostriction and thermal expansion of this series to ...