@article{lee_kan_whangbo_bussmann-holder_simon_2012, title={Spin/Charge Redistributions and Oxygen Atom Displacements Induced by Spin Flip and Hole Doping in the CuO2 Layer of High-Temperature Superconductors}, volume={25}, ISSN={["1557-1939"]}, DOI={10.1007/s10948-011-1208-3}, number={1}, journal={JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM}, author={Lee, C. and Kan, E. J. and Whangbo, M. -H. and Bussmann-Holder, A. and Simon, A.}, year={2012}, month={Jan}, pages={55–59} }
 @article{zhang_kan_whangbo_2011, title={Density Functional Investigation of the Difference in the Magnetic Structures of the Layered Triangular Antiferromagnets CuFeO2 and AgCrO2}, volume={23}, ISSN={["1520-5002"]}, DOI={10.1021/cm2011567}, abstractNote={The layered triangular antiferromagnets CuFeO2 and AgCrO2 exhibit ferroelectric polarization when they adopt a helical spiral-spin magnetic structure. Application of magnetic field parallel to the c-axis or doping Fe sites with Al or Ga is necessary for CuFeO2 to have a helical spiral spin order. However, AgCrO2 adopts a helical spiral spin order in the absence of such extrinsic factors. A probable cause for this difference between the two systems was examined by evaluating the relative stabilities of their helical spiral and collinear spin structures on the basis of density functional calculations. In contrast to the case of AgCrO2, the collinear ↑↑↓↓ state is only slightly higher in energy than the helical spiral-spin state Qa+b in CuFeO2 so that extrinsic factors such as oxygen vacancy and applied magnetic field can influence whether CuFeO2 adopts the ↑↑↓↓ or Qa+b structure.}, number={18}, journal={CHEMISTRY OF MATERIALS}, author={Zhang, Yuemei and Kan, Erjun and Whangbo, Myung-Hwan}, year={2011}, month={Sep}, pages={4181–4185} }
 @article{zhang_kan_xiang_villesuzanne_whangbo_2011, title={Density Functional Theory Analysis of the Interplay between Jahn-Teller Instability, Uniaxial Magnetism, Spin Arrangement, Metal-Metal Interaction, and Spin-Orbit Coupling in Ca3CoMO6 (M = Co, Rh, Ir)}, volume={50}, ISSN={["0020-1669"]}, DOI={10.1021/ic1022278}, abstractNote={In the isostructural oxides Ca(3)CoMO(6) (M = Co, Rh, Ir), the CoMO(6) chains made up of face-sharing CoO(6) trigonal prisms and MO(6) octahedra are separated by Ca atoms. We analyzed the magnetic and electronic properties of these oxides on the basis of density functional theory calculations including on-site repulsion and spin-orbit coupling, and examined the essential one-electron pictures hidden behind results of these calculations. Our analysis reveals an intimate interplay between Jahn-Teller instability, uniaxial magnetism, spin arrangement, metal-metal interaction, and spin-orbit coupling in governing the magnetic and electronic properties of these oxides. These oxides undergo a Jahn-Teller distortion, but their distortions are weak, so that their trigonal-prism Co(n+) (n = 2, 3) ions still give rise to strong easy-axis anisotropy along the chain direction. As for the d-state split pattern of these ions, the electronic and magnetic properties of Ca(3)CoMO(6) (M = Co, Rh, Ir) are consistent with d(0) < (d(2), d(-2)) < (d(1), d(-1)) but not with (d(2), d(-2)) < d(0) < (d(1), d(-1)). The trigonal-prism Co(3+) ion in Ca(3)Co(2)O(6) has the L = 2 configuration (d(0))(1)(d(2), d(-2))(3)(d(1), d(-1))(2) because of the metal-metal interaction between adjacent Co(3+) ions in each Co(2)O(6) chain, which is mediated by their z(2) orbitals, and the spin-orbit coupling of the trigonal-prism Co(3+) ion. The spins in each CoMO(6) chain of Ca(3)CoMO(6) prefer the ferromagnetic arrangement for M = Co and Rh but the antiferromagnetic arrangement for M = Ir. The octahedral M(4+) ion of Ca(3)CoMO(6) has the (1a)(1)(1e)(4) configuration for M = Rh but the (1a)(2)(1e)(3) configuration for M = Ir, which arises from the difference in the spin-orbit coupling of the M(4+) ions and the Co···M metal-metal interactions.}, number={5}, journal={INORGANIC CHEMISTRY}, author={Zhang, Yuemei and Kan, Erjun and Xiang, Hongjun and Villesuzanne, Antoine and Whangbo, Myung-Hwan}, year={2011}, month={Mar}, pages={1758–1766} }
 @article{xiang_kan_whangbo_lee_wei_gong_2011, title={Single-ion anisotropy, Dzyaloshinskii-Moriya interaction, and negative magnetoresistance the spin-1/2 pyrochlore R2V2O7}, volume={83}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.83.174402}, abstractNote={semicore level asthe reference, we find that the VBM level of the FM stateis almost the same (only about 0.01 eV higher) as that ofthe AFM state. Therefore the CBM of the AFM state ismuch higher than that of the FM state. The reason why theAFM state has a higher CBM and thus a larger band gap isillustrated in Fig. 3(d). When the spins of two neighboringV ions have an FM coupling, the up-spin}, number={17}, journal={PHYSICAL REVIEW B}, author={Xiang, H. J. and Kan, E. J. and Whangbo, M. -H. and Lee, C. and Wei, Su-Huai and Gong, X. G.}, year={2011}, month={May} }
 @article{tian_lee_kan_wu_whangbo_2010, title={Analysis of the Magnetic Structure and Ferroelectric Polarization of Monoclinic MnSb2S4 by Density Functional Theory Calculations}, volume={49}, ISSN={["1520-510X"]}, DOI={10.1021/ic101351b}, abstractNote={Monoclinic MnSb(2)S(4) consists of MnS(4) chains made up of edge-sharing MnS(6) octahedra and adopts a (0, 0.369, 0) magnetic superstructure below 25 K. This ordered magnetic structure, in which the spins of each MnS(4) chain possess a helical spin arrangement, has C(2)' symmetry. On the basis of density functional theory calculations, we explored the origin of the observed noncollinear spin arrangement of MnSb(2)S(4) by evaluating its spin exchanges to find that spin exchanges are frustrated not only within each MnS(4) chain but also between adjacent MnS(4) chains. Our analysis predicts that MnSb(2)S(4) is a multiferroic with a ferroelectric polarization of ∼14 μC/m(2) along the chain direction, and a field-induced reversal of the ferroelectric polarization of MnSb(2)S(4) can occur by reversing the direction of the helical spin rotation in each MnS(4) chain.}, number={23}, journal={INORGANIC CHEMISTRY}, author={Tian, Chuan and Lee, Changhoon and Kan, Erjun and Wu, Fang and Whangbo, Myung-Hwan}, year={2010}, month={Dec}, pages={10956–10959} }
 @article{kan_xiang_wu_lee_yang_whangbo_2010, title={Ferrimagnetism in zigzag graphene nanoribbons induced by main-group adatoms}, volume={96}, number={10}, journal={Applied Physics Letters}, author={Kan, E. and Xiang, H. J. and Wu, F. and Lee, C. and Yang, J. L. and Whangbo, M. H.}, year={2010} }
 @article{kan_xiang_lee_wu_yang_whangbo_2010, title={Ferroelectricity in Perovskites with s(0) A-Site Cations: Toward Near-Room-Temperature Multiferroics}, volume={49}, ISSN={["1433-7851"]}, DOI={10.1002/anie.200905997}, abstractNote={materials is based on perovskites, ABO3, with two different cations A and B (for example A 2+ and B 4+ or A 3+ and B 3+ ), in which corner-sharing BO6 octahedra form the three-dimen- sional lattice with every B8 cube containing one A cation. An ideal cubic perovskite, in which the B-OB bonds are linear with A located at the center of each B8 cube (thus forming a AO12 polyhedron), is expected when the tolerance factor t = (rO + rA)/ ffiffiffi 2 p (r O+rB) is unity (rA and rB are the ionic radii of the A and B cations, respectively, with rO as that of the O 2� anion). In most cases, the A cations are small, so that t < 1 and the AO bonds are too long to maintain the ideal cubic structure. Consequently, the A cation moves away from the center of the B8 cube, which is accompanied by the bending of the B-O-B bonds and the rotation of the BO6 octahedra to form a lower-coordinate AOn polyhedron (n < 12) with short AO bonds. The distortion of the ideal cubic perovskite toward a non-centrosymmetric FE structure requires another local instability apart from t < 1, namely, the second-order Jahn-Teller (SOJT) instability (4-6) of the A-site and/or B-site}, number={9}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Kan, Erjun and Xiang, Hongjun and Lee, Changhoon and Wu, Fang and Yang, Jinlong and Whangbo, Myung-Hwan}, year={2010}, pages={1603–1606} }
 @article{dorolti_cario_corraze_janod_vaju_koo_kan_whangbo_2010, title={Half-Metallic Ferromagnetism and Large Negative Magnetoresistance in the New Lacunar Spinel GaTi3VS8}, volume={132}, ISSN={["0002-7863"]}, DOI={10.1021/ja908128b}, abstractNote={The lacunar spinel compounds GaTi(4-x)V(x)S(8) (0 < x < 4), consisting of Ti(4-x)V(x) tetrahedral clusters, were prepared and their structures were determined by powder X-ray diffraction. The electronic structures of GaTi(4-x)V(x)S(8) (x = 0, 1, 2, 3) were examined by density functional calculations, and the electrical resistivity and magnetic susceptibility of these compounds were measured. Our calculations predict that GaTi(3)VS(8) is a ferromagnetic half-metal, and this prediction was confirmed by magnetotransport experiments performed on polycrystalline samples of GaTi(3)VS(8). The latter reveal a large negative magnetoresistance (up to 22% at 2 K), which is consistent with the intergrain tunnelling magnetoresistance expected for powder samples of a ferromagnetic half-metal and indicates the presence of high spin polarization greater than 53% in GaTi(3)VS(8).}, number={16}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Dorolti, Eugen and Cario, Laurent and Corraze, Benoit and Janod, Etienne and Vaju, Cristian and Koo, Hyun-Joo and Kan, Erjun and Whangbo, Myung-Hwan}, year={2010}, month={Apr}, pages={5704–5710} }
 @article{wu_kan_whangbo_2010, title={On the Importance of the Interplaquette Spin Exchanges in Na3RuO4: Density Functional Theory Analysis of the Spin Exchange and Magnetic Properties}, volume={49}, ISSN={["1520-510X"]}, DOI={10.1021/ic902568v}, abstractNote={Na(3)RuO(4) contains layers of high-spin Ru(5+) d(3) ions grouped into isolated four-membered plaquettes. To determine the spin-lattice appropriate for Na(3)RuO(4), we evaluated the intraplaquette exchanges J(1), J(2), and J(3) as well as the interplaquette exchanges J(4) and J(5) by performing mapping analysis based on first-principles density functional theory calculations. In addition, we examined how the trends in the calculated J(1)-J(5) are related to the distortions of the RuO(6) octahedra in the four-membered plaquettes. The spin-lattice of Na(3)RuO(4) is described by the intraplaquette exchanges J(1) and J(2) plus the interplaquette exchanges J(4) and J(5), with spin frustration arising from the (J(1), J(2), J(1)) and (J(5), J(4), J(5)) triangles. The trends in the calculated J(1)-J(5) reflect the distortions of the RuO(6) octahedra in the four-membered plaquettes.}, number={6}, journal={INORGANIC CHEMISTRY}, author={Wu, Fang and Kan, Erjun and Whangbo, Myung-Hwan}, year={2010}, month={Mar}, pages={3025–3028} }
 @article{ji_kan_whangbo_kim_qiu_matsuda_yoshida_hiroi_green_ziman_et al._2010, title={Orbital order and partial electronic delocalization in a triangular magnetic metal Ag2MnO2}, volume={81}, ISSN={["1098-0121"]}, DOI={10.1103/physrevb.81.094421}, abstractNote={Unconventional collective behaviors often arise whenelectron-electron Coulomb repulsion is neither strong lead-ing to electron localization and magnetism nor weak lead-ing to electron delocalization and metallicity 3+. A well-knownexample is the high-temperature superconductivity found incuprates and iron superconductors.}, number={9}, journal={PHYSICAL REVIEW B}, author={Ji, S. and Kan, E. J. and Whangbo, M. -H. and Kim, J. -H. and Qiu, Y. and Matsuda, M. and Yoshida, H. and Hiroi, Z. and Green, M. A. and Ziman, T. and et al.}, year={2010}, month={Mar} }
 @article{kan_xiang_wu_tian_lee_yang_whangbo_2010, title={Prediction for room-temperature half-metallic ferromagnetism in the half-fluorinated single layers of BN and ZnO}, volume={97}, number={12}, journal={Applied Physics Letters}, author={Kan, E. J. and Xiang, H. J. and Wu, F. and Tian, C. and Lee, C. and Yang, J. L. and Whangbo, M. H.}, year={2010} }
 @inproceedings{tong_kremer_kohler_simon_lee_kan_whangbo_2010, title={The layered ferromagnet Cs2AgF4: Antiferromagnetic inter-layer coupling driven by magnetic dipole-dipole interactions}, volume={225}, number={11}, booktitle={Zeitschrift fur Kristallographie}, author={Tong, J. W. and Kremer, R. K. and Kohler, J. and Simon, A. and Lee, C. H. and Kan, E. and Whangbo, M. H.}, year={2010}, pages={498–503} }
 @article{wu_kan_tian_whangbo_2010, title={Theoretical Analysis of the Spin Exchange and Magnetic Dipole-Dipole Interactions Leading to the Magnetic Structure of Ni3TeO6}, volume={49}, ISSN={["1520-510X"]}, DOI={10.1021/ic101022f}, abstractNote={The origin of the collinear antiferromagnetic magnetic structure of Ni(3)TeO(6) below 52 K was analyzed by calculating its spin exchanges on the basis of density functional calculations, and the cause for the parallelc-spin orientation found for this magnetic structure by calculating the spin-orbit coupling and magnetic dipole-dipole interaction energies. The calculated exchanges correctly predict the observed magnetic structure below 52 K, and lead practically to no spin frustration. The perpendicularc- and parallelc-spin orientations are predicted by the spin-orbit coupling and the magnetic dipole-dipole interactions, respectively. However, the magnetic dipole-dipole interactions are stronger than the spin-orbit coupling interactions, and hence are responsible for the spin orientation observed for Ni(3)TeO(6).}, number={16}, journal={INORGANIC CHEMISTRY}, author={Wu, Fang and Kan, Erjun and Tian, Chuan and Whangbo, Myung-Hwan}, year={2010}, month={Aug}, pages={7545–7548} }
 @article{lee_kan_xiang_whangbo_2010, title={Theoretical Investigation of the Magnetic Structure and Ferroelectric Polarization of the Multiferroic Langasite Ba3NbFe3Si2O14}, volume={22}, ISSN={["0897-4756"]}, DOI={10.1021/cm101441p}, abstractNote={The multiferroic langasite Ba3NbFe3Si2O14, crystallizing in a noncentrosymetric space group, has sheets of Fe3+ ions parallel to the ab plane. It adopts a chiral magnetic order below TN = 26 K that has a superstructure with propagation vector (0, 0, ∼1/7). The spin frustration causing this magnetic structure of Ba3NbFe3Si2O14 was examined by evaluating its spin exchange interactions on the basis of density functional calculations and also by calculating its magnetic dipole−dipole interactions. The contribution of the chiral magnetic structure to the ferroelectric polarization of Ba3NbFe3Si2O14 below TN was estimated by Berry phase calculations. The spin exchanges of Ba3NbFe3Si2O14 are frustrated in each //ab sheet and between adjacent sheets of Fe3+ ions. The helical spin rotation along the c axis occurs to minimize the intersheet spin frustration as well as the intersheet magnetic dipole−dipole interactions. The ferroelectric polarization of Ba3NbFe3Si2O14 estimated from calculations is in good agreement...}, number={18}, journal={CHEMISTRY OF MATERIALS}, author={Lee, Changhoon and Kan, Erjun and Xiang, Hongjun and Whangbo, Myung-Hwan}, year={2010}, month={Sep}, pages={5290–5295} }
 @article{xiang_kan_wei_gong_whangbo_2010, title={Thermodynamically stable single-side hydrogenated graphene}, volume={82}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.82.165425}, abstractNote={H. J. Xiang,1 E. J. Kan,2 Su-Huai Wei,3 X. G. Gong,1 and M.-H. Whangbo2 1Key Laboratory of Computational Physical Sciences, Ministry of Education, and Department of Physics, Fudan University, Shanghai 200433, People’s Republic of China 2Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA 3National Renewable Energy Laboratory, Golden, Colorado 80401, USA Received 29 August 2010; published 13 October 2010}, number={16}, journal={PHYSICAL REVIEW B}, author={Xiang, H. J. and Kan, E. J. and Wei, Su-Huai and Gong, X. G. and Whangbo, M. -H.}, year={2010}, month={Oct} }
 @article{tian_kan_lee_whangbo_2010, title={pi-Back-Donation Effect of the Cyanide Ligands on the Electron Correlation and Charge Transfer in Prussian Blue RbMn[Fe(CN)(6)]}, volume={49}, ISSN={["1520-510X"]}, DOI={10.1021/ic902577r}, abstractNote={The temperature-induced charge transfer between the Mn and Fe sites in RbMn[Fe(CN)(6)] was analyzed by density functional theory calculations. Our analysis indicates that the extent of electron correlation (equivalently, the pairing energy or the on-site repulsion) is much greater for the Mn(n+) ion than for the Fe(n+) ion (n = 2, 3). This surprising and counterintuitive finding is a consequence of the pi-back-donation effect of the CN ligands.}, number={7}, journal={INORGANIC CHEMISTRY}, author={Tian, Chuan and Kan, Erjun and Lee, Changhoon and Whangbo, Myung-Hwan}, year={2010}, month={Apr}, pages={3086–3088} }
 @article{xiang_kan_wei_whangbo_yang_2009, title={"Narrow" Graphene Nanoribbons Made Easier by Partial Hydrogenation}, volume={9}, ISSN={["1530-6992"]}, DOI={10.1021/nl902198u}, abstractNote={It is highly desirable to produce narrow-width graphene nanoribbons (GNRs) with smooth edges in large scale. In an attempt to solve this difficult problem, we examined the hydrogenation of GNRs on the basis of first principles density functional calculations. Our study shows that narrow GNRs can be readily obtained from wide GNRs by partial hydrogenation. The hydrogenation of GNRs starts from the edges of GNRs and proceeds gradually toward the middle of the GNRs so as to maximize the number of carbon-carbon pi-pi bonds, hence effectively leading to narrower GNRs. Furthermore, the partially hydrogenated wide GNRs have similar electronic and magnetic properties as those of the narrow GNRs representing their graphene parts. Therefore, partial hydrogenation of wide GNRs should be a practical and reliable method to produce narrow GNRs in large scale.}, number={12}, journal={NANO LETTERS}, author={Xiang, Hongjun and Kan, Erjun and Wei, Su-Huai and Whangbo, Myung-Hwan and Yang, Jinlong}, year={2009}, month={Dec}, pages={4025–4030} }
 @article{kan_xiang_zhang_lee_whangbo_2009, title={Density-functional analysis of spin exchange and ferroelectric polarization in AgCrO2}, volume={80}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.80.104417}, abstractNote={Density-functional calculations were carried out for AgCrO2 to examine its spin exchange and ferroelectric polarization. In the multiferroic state of AgCrO2 the triangular spin lattice of each CrO2 layer forms parallel chains with helical-spin order. The spin exchange interactions of AgCrO2 are strongly frustrated both within and between adjacent CuO2 layers, which gives rise to the observed helical-spin order. The observed ferroelectric polarization of AgCrO2 is not caused by individual helical-spin chains, but by the spiral-spin chain structures that propagate between the helical-spin chains.}, number={10}, journal={PHYSICAL REVIEW B}, author={Kan, E. J. and Xiang, H. J. and Zhang, Y. and Lee, C. and Whangbo, M. -H.}, year={2009}, month={Sep} }
 @article{wu_kan_xiang_wei_whangbo_yang_2009, title={Magnetic states of zigzag graphene nanoribbons from first principles}, volume={94}, number={22}, journal={Applied Physics Letters}, author={Wu, F. and Kan, E. J. and Xiang, H. J. and Wei, S. H. and Whangbo, M. H. and Yang, J. L.}, year={2009} }
 @article{kan_xiang_yang_whangbo_2009, title={Magnetism of semiconductor-based magnetic tunnel junctions under electric field from first principles}, volume={94}, number={25}, journal={Applied Physics Letters}, author={Kan, E. J. and Xiang, H. J. and Yang, J. L. and Whangbo, M. H.}, year={2009} }
 @article{xiang_kan_wei_whangbo_yang_2009, title={Origin of the Ising ferrimagnetism and spin-charge coupling in LuFe2O4}, volume={80}, ISSN={["1098-0121"]}, DOI={10.1103/physrevb.80.132408}, abstractNote={The spin-ordering and spin-charge coupling in ${\text{LuFe}}_{2}{\text{O}}_{4}$ were investigated on the basis of density functional calculations and Monte Carlo simulations. The 2:1 ferrimagnetism arises from the strong antiferromagnetic intrasheet ${\text{Fe}}^{3+}{\text{-Fe}}^{3+}$ and ${\text{Fe}}^{3+}{\text{-Fe}}^{2+}$ as well as some substantial antiferromagnetic ${\text{Fe}}^{2+}{\text{-Fe}}^{3+}$ intersheet spin exchange interactions. The giant magnetocapacitance at room temperature and the enhanced electric polarization at 240 K of ${\text{LuFe}}_{2}{\text{O}}_{4}$ are explained by the strong spin-charge coupling.}, number={13}, journal={PHYSICAL REVIEW B}, author={Xiang, H. J. and Kan, E. J. and Wei, Su-Huai and Whangbo, M. -H. and Yang, Jinlong}, year={2009}, month={Oct} }