@article{golubev_nuss_kremer_gordon_whangbo_ritter_weber_wessel_2020, title={Two-dimensional magnetism in alpha-CuV2O6}, volume={102}, ISSN={["2469-9969"]}, DOI={10.1103/PhysRevB.102.014436}, abstractNote={Several previous studies reported that a one-dimensional Heisenberg chain model is inadequate in describing the magnetic properties of the low-dimensional quantum antiferromagnet $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{CuV}}_{2}{\mathrm{O}}_{6}$, but the origin for this observation has remained unclear. We have reinvestigated the magnetic properties of $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{CuV}}_{2}{\mathrm{O}}_{6}$ and found that our anisotropic magnetic susceptibility, neutron-powder diffraction, and electron paramagnetic spin-resonance measurements are in good agreement with extensive density-functional theory ($\mathrm{DFT}+U$) total energy calculations which indicate that the correct spin lattice model for $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{CuV}}_{2}{\mathrm{O}}_{6}$ is rather a $S=1/2$ 2D-Heisenberg antiferromagnetic lattice. The magnetic susceptibility data are well described by a rectangular Heisenberg antiferromagnet with anisotropy ratio $\ensuremath{\alpha}\ensuremath{\sim}$ 0.7 consistent with the DFT results. Quantum Monte Carlo simulations of the magnetic susceptibilities for a rectangular lattice Heisenberg antiferromagnet were performed in the anisotropy range 0.5 $\ensuremath{\le}\ensuremath{\alpha}\ensuremath{\le}$ 1.0. The results of the Quantum Monte Carlo calculations were cast into a Pad\'e approximant which was used to fit the temperature-dependent magnetic susceptibility data. Neutron-powder-diffraction measurements were used to conclusively solve the collinear antiferromagnetic structure of $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{CuV}}_{2}{\mathrm{O}}_{6}$ below the N\'eel temperature of $\ensuremath{\sim}22.4$ K.}, number={1}, journal={PHYSICAL REVIEW B}, author={Golubev, A. M. and Nuss, J. and Kremer, R. K. and Gordon, E. E. and Whangbo, M-H and Ritter, C. and Weber, L. and Wessel, S.}, year={2020}, month={Jul} }
 @article{lomnytska_dzevenko_babizhetskyy_toma_smolyak_gordon_whangbo_koehler_2018, title={Interaction of tantalum, titanium and phosphorus at 1070 K: Phase diagram and structural chemistry}, volume={732}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2017.10.247}, abstractNote={The solid state phase diagram for the equilibria of the ternary Ta-Ti-P system was established by X-ray powder diffraction at T = 1070 K in the region up to 67 at.% P. Isostructural compounds Ta3P and Ti3P (both Ti3P-type) form a continuous series of substitution-type solid solutions. The majority of binary compounds form substitution-type solid solutions, in which the substitution of Ti for Ta, or Ta for Ti, takes place. The crystal structure investigation of the new ternary phosphide demonstrates that this phase is isotypical to the OsGe2 structure type and has a small homogeneity range, which can be described by the formula Та1-xТіxР2 (x = 0.07(3)−0.145(7), space group C2/m, a = 8.8556(9)−8.8446(2), b = 3.2654(4)−3.2605(1), c = 7.4846(8)−7.4741(1) Å, β = 119.307(2)−119.308(1)°). Our density functional theory (DFT) electronic structure calculations show that the stoichiometric composition TaP2 has no electronic instability, although it does not exist under the thermal conditions used in present study. The addition of a small amount of Ti leads to a ternary phase Та1-xТіxР2 (x = 0.07(3)−0.145(7)) with a higher thermal stability compared to TaP2.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Lomnytska, Ya. and Dzevenko, M. and Babizhetskyy, V. and Toma, O. and Smolyak, O. and Gordon, E. E. and Whangbo, M. -H. and Koehler, J.}, year={2018}, month={Jan}, pages={777–783} }
 @article{golubev_bruecher_schulz_kremer_schmidt_gordon_whangbo_2018, title={Low-Dimensional Magnetic Properties of Natural and Synthetic Mixite (Bi,Ca)Cu-6(OH)(6)(AsO4)(3)center dot nH(2)O (n approximate to 3) and Goudeyite YCu6(OH)(6)(AsO4)(3)center dot nH(2)O (n approximate to 3)}, volume={644}, ISSN={["1521-3749"]}, DOI={10.1002/zaac.201800344}, abstractNote={The structural, vibrational, and especially the magnetic properties of natural and synthetic polycrystalline samples of the minerals mixite with composition (Bi,Ca)Cu 6 (OH) 6 (AsO 4 ) 3 · n H 2 O ( n ≈ 3) and goudeyite with composition YCu 6 (OH) 6 (AsO 4 ) 3 · n H 2 O ( n ≈ 3) were investigated. The magnetic susceptibilities are characterized by low‐dimensional antiferromagnetic short range ordering and can be well fitted by the theoretical susceptibilities of a spin S = 1/2 alternating Heisenberg chain with nearest‐neighbor spin exchange ranging between 200 K and 130 K for natural mixite and synthetic goudeyite, respectively. The alternation parameters, i.e. the ratios of nearest and next‐nearest neighbor spin exchange range between 0.52 for natural mixite and 0.75 for synthetic mixite and goudeyite, respectively. The experimentally observed spin exchange parameters are consistent with DFT calculations of the spin exchange parameters.}, number={24}, journal={ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE}, author={Golubev, Aleksandr and Bruecher, Eva and Schulz, Armin and Kremer, Reinhard K. and Schmidt, Franz X. and Gordon, Elija E. and Whangbo, Myung-Hwan}, year={2018}, month={Dec}, pages={1782–1790} }
 @article{leiner_oh_kolesnikov_stone_le_kenny_powell_mourigal_gordon_whangbo_et al._2018, title={Magnetic excitations of the Cu2+ quantum spin chain in Sr3CuPtO6}, volume={97}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.97.104426}, abstractNote={We report the magnetic excitation spectrum as measured by inelastic neutron scattering for a polycrystalline sample of Sr3CuPtO6. Modeling the data by the 2+4 spinon contributions to the dynamical susceptibility within the chains, and with interchain coupling treated in the random phase approximation, accounts for the major features of the powder-averaged structure factor. The magnetic excitations broaden considerably as temperature is raised, persisting up to above 100 K and displaying a broad transition as previously seen in the susceptibility data. No spin gap is observed in the dispersive spin excitations at low momentum transfer, which is consistent with the gapless spinon continuum expected from the coordinate Bethe ansatz. However, the temperature dependence of the excitation spectrum gives evidence of some very weak interchain coupling.}, number={10}, journal={PHYSICAL REVIEW B}, author={Leiner, J. C. and Oh, Joosung and Kolesnikov, A. I. and Stone, M. B. and Le, Manh Duc and Kenny, E. P. and Powell, B. J. and Mourigal, M. and Gordon, E. E. and Whangbo, M. -H. and et al.}, year={2018}, month={Mar} }
 @article{lu_mentre_gordon_whangbo_wattiaux_duttine_tiercelin_kabbour_2017, title={A comprehensive study of magnetic exchanges in the layered oxychalcogenides Sr(3)Fe(2)O(5)Cu(2)Q(2) (Q = S, Se)}, volume={444}, ISSN={["1873-4766"]}, DOI={10.1016/j.jmmm.2017.07.026}, abstractNote={The layered oxysulfide Sr3Fe2O5Cu2S2 was prepared, and its crystal structure and magnetic properties were characterized by synchrotron X-ray diffraction (XRD), powder neutron diffraction (PND), Mössbauer spectroscopy measurements and by density functional theory (DFT) calculations. In addition, the spin exchange interactions leading to the ordered magnetic structure of Sr3Fe2O5Cu2S2 were compared with those of its selenium analogue Sr3Fe2O5Cu2Se2. The oxysulfide Sr3Fe2O5Cu2S2 adopts a G-type antiferromagnetic (AFM) structure at a temperature in the range 485–512 K, which is comparable with the three-dimensional (3D) AFM ordering temperature, TN ≈ 490 K, found for Sr3Fe2O5Cu2Se2. Consistent with this observation, the spin exchange interactions of the magnetic (Sr3Fe2O5)2+ layers are slightly greater (but comparable) for oxysulfide than for the oxyselenide. Attempts to reduce or oxidize Sr3Fe2O5Cu2S2 using topochemical routes yield metallic Fe.}, journal={JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS}, author={Lu, Minfeng and Mentre, Olivier and Gordon, Elijah E. and Whangbo, Myung-Hwan and Wattiaux, Alain and Duttine, Mathieu and Tiercelin, Nicolas and Kabbour, Houria}, year={2017}, month={Dec}, pages={147–153} }
 @article{zoellner_gordon_maggard_2017, title={A small bandgap semiconductor, p-type MnV2O6, active for photocatalytic hydrogen and oxygen production}, volume={46}, ISSN={["1477-9234"]}, DOI={10.1039/c7dt00780a}, abstractNote={Extensive research has been conducted with the goal to find a single bandgap material that can absorb visible light and efficiently drive the catalysis of water to both hydrogen and oxygen. The p-type MnV2O6 (C2/m, Z = 2, a = 9.289 Å, b = 3.535 Å, and c = 6.763 Å, β = 112.64°), synthesized via solid-state techniques, was investigated for its potential use in the visible-light photocatalysis of water. Mott-Schottky analysis was used to experimentally determine the energetic positions of the valence and conduction bands as +0.985 V and -0.464 V, respectively, at pH 5.68 vs. RHE. These are found to be suitable potentials to drive the reduction and oxidation of water under irradiation. The bandgap transitions, probed using spin-polarized density functional calculations, consist of the excitation of electrons from the half-filled Mn 3d5 orbitals to the empty V 3d0 orbitals. Both hydrogen and oxygen gas were observed as products during suspended-particle photocatalysis experiments under visible-light irradiation. The rate and total moles of gas produced were found to increase with the reaction temperature. As the temperature was raised from 30 °C to 37 °C and 44 °C, the moles of hydrogen produced over 6 hours increased by ∼1.5 and ∼2.5 times. Only oxygen is produced in pure water, showing that methanol is needed to drive hydrogen production.}, number={32}, journal={DALTON TRANSACTIONS}, author={Zoellner, Brandon and Gordon, Elijah and Maggard, Paul A.}, year={2017}, month={Aug}, pages={10657–10664} }
 @article{barroux_jiang_paul_massuyeau_geois_gordon_whangbo_jobic_gautier_2017, title={Fine-Tuning the Properties of Doped Multifunctional Materials by Controlled Reduction of Dopants}, volume={23}, ISSN={["1521-3765"]}, DOI={10.1002/chem.201605707}, abstractNote={Abstract}, number={13}, journal={CHEMISTRY-A EUROPEAN JOURNAL}, author={Barroux, Hugo and Jiang, Tengfei and Paul, Camille and Massuyeau, Florian and Geois, Romain and Gordon, Elijah E. and Whangbo, Myung-Hwan and Jobic, Stephane and Gautier, Romain}, year={2017}, month={Mar}, pages={2998–3001} }
 @article{gordon_koo_deng_koehler_whangbo_2017, title={Group of Quantum Bits Acting as a Bit Using a Single-Domain Ferromagnet of Uniaxial Magnetic Ions}, volume={18}, ISSN={["1439-7641"]}, DOI={10.1002/cphc.201700609}, abstractNote={Read/write operations with individual quantum bits (i.e., qbits) are a challenging problem to solve in quantum computing. To alleviate this difficulty, we considered the possibility of using a group of qbits that act collectively as a bit (hereafter, a group bit or a gbit, in short). A promising candidate for a gbit is a single-domain ferromagnet (SDF) independent of its size, which can be prepared as a magnet of well-separated uniaxial magnetic ions (UMIs) at sites of no electric dipole moment with their uniaxial axes aligned along one common direction. When magnetized, the UMIs of such a magnet have a ferromagnetic (FM) arrangement and the resulting SDF becomes a gbit with its two opposite moment orientations representing the |0⟩ and |1⟩ states of a bit. We probed the requirements for such magnets and identified several 2H-perovskites as materials satisfying these requirements.}, number={16}, journal={CHEMPHYSCHEM}, author={Gordon, Elijah E. and Koo, Hyun-Joo and Deng, Shuiquan and Koehler, Juergen and Whangbo, Myung-Hwan}, year={2017}, month={Aug}, pages={2147–2150} }
 @article{behrh_isobe_massuyeau_serier-brault_gordon_koo_whangbo_gautier_jobic_2017, title={Oxygen-Vacancy-Induced Midgap States Responsible for the Fluorescence and the Long-Lasting Phosphorescence of the Inverse Spinel Mg(Mg,Sn)O-4}, volume={29}, ISSN={["1520-5002"]}, DOI={10.1021/acs.chemmater.6b03906}, abstractNote={Samples of inverse spinel Mg2SnO4 were prepared using a ceramic method, their phosphorescence phenomenon was probed by optical measurements, and its cause was explored on the basis of density functional theory calculations for model structures of Mg2SnO4 with oxygen vacancies VO. Mg2SnO4 exhibits long-lasting luminescence at two different wavelength regions, peaking at ∼498 and ∼755 nm. A Sn-VO-Sn defect plus a Mg vacancy VMg away from the VO generates the empty midgap states, σSn-Sn and σSn-Sn*, localized at the Sn-VO-Sn defect, while an oxygen vacancy VO between adjacent Sn4+ and Mg2+ sites creates a filled midgap state Sn2+ (5s2 lone pair) lying below the σSn-Sn level. The long-lasting luminescence at two different wavelength regions and the up-conversion photostimulated luminescence observed for undoped Mg2SnO4 are well explained by considering the σSn-Sn* level as the trapping level for a photogenerated electron.}, number={3}, journal={CHEMISTRY OF MATERIALS}, author={Behrh, Gaganpreet Kaur and Isobe, Masahiko and Massuyeau, Florian and Serier-Brault, Helene and Gordon, Elijah E. and Koo, Hyun-Joo and Whangbo, Myung-Hwan and Gautier, Romain and Jobic, Stephane}, year={2017}, month={Feb}, pages={1069–1075} }
 @article{lee_an_gordon_ji_park_shim_lim_whangbo_2017, title={Seebeck Coefficients of Layered BiCuSeO Phases: Analysis of Their Hole-Density Dependence and Quantum Confinement Effect}, volume={29}, ISSN={["1520-5002"]}, DOI={10.1021/acs.chemmater.7b00028}, abstractNote={Hole-doped layered BiCuSeO phases include substitutionally doped Bi1–xAxCuSeO (A = alkali, alkaline earth) as well as vacancy-doped Bi1−δCu1-γSeO and Bi1−δCuSeO. To probe how their Seebeck coefficients are related to their hole density p, we calculated the Seebeck coefficient for defect-free BiCuSeO as a function of the hole density, which is generated by lowering the Fermi level from the valence band maximum (VBM). In addition, we calculated the Seebeck coefficient for Bi1−δCuSeO (δ = 1/32, 1/16) with a large number of Bi vacancies. The Seebeck coefficients of the hole-doped BiCuSeO phases are governed by the electronic states lying within ∼0.5 eV from the VBM. These states are composed of largely Cu 3d xz/yz and Se 4p x/y states and possess the character of a uniform one-dimensional (1D) chain rather than a uniform two-dimensional (2D) lattice expected for a layered phase. The observed S-vs-p relationship for Bi1–xAxCuSeO (A = alkali, alkaline earth) as well as Bi1−δCu1-γSeO (δ = 0, 0.025; γ = 0, 0.025)...}, number={5}, journal={CHEMISTRY OF MATERIALS}, author={Lee, Changhoon and An, Tae-Ho and Gordon, Elijah E. and Ji, Hyo Seok and Park, Chan and Shim, Ji-Hoon and Lim, Young Soo and Whangbo, Myung-Hwan}, year={2017}, month={Mar}, pages={2348–2354} }
 @article{koo_gordon_whangbo_2017, title={Single-Domain Ferromagnet of Noncentrosymmetric Uniaxial Magnetic Ions and Magnetoelectric Interaction}, volume={56}, ISSN={["1521-3773"]}, DOI={10.1002/anie.201701699}, abstractNote={Abstract}, number={34}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Koo, Hyun-Joo and Gordon, Elijah E. and Whangbo, Myung-Hwan}, year={2017}, month={Aug}, pages={10196–10199} }
 @article{cheng_gordon_whangbo_deng_2017, title={Superconductivity Induced by Oxygen Doping in Y2O2Bi}, volume={56}, ISSN={["1521-3773"]}, DOI={10.1002/anie.201701427}, abstractNote={Abstract}, number={34}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Cheng, Xiyue and Gordon, Elijah E. and Whangbo, Myung-Hwan and Deng, Shuiquan}, year={2017}, month={Aug}, pages={10123–10126} }
 @article{kovrugin_gordon_kasapbasi_whangbo_colmont_siidra_colis_krivovichev_mentre_2016, title={Bonding Scheme, Hydride Character, and Magnetic Paths of (HPO3)(2-) Versus (SeO3)(2-) Building Units in Solids}, volume={120}, ISSN={["1932-7447"]}, DOI={10.1021/acs.jpcc.5b10889}, abstractNote={The abilities of the (HPO3)2– and (SeO3)2– anions as structure building units and as spin exchange paths between magnetic ions were investigated by preparing and analyzing the isostructural Fe2(SeO3)3 and Fe2(HPO3)3. In both compounds, the face-sharing Fe2O9 dimers are interconnected into chains by the (HPO3)2– and (SeO3)2– anions. The (HPO3)2– is the structural counterpart of the Se electron lone pair of (SeO3)2– due to the weak hydride character of the terminal hydrogen. However, they differ considerably as spin exchange paths between magnetic cations. Both compounds exhibit an effective magnetic dimer behavior, unexpectedly arising from the interdimer Fe—O···O—Fe exchange along the chain, but weaker in Fe2(HPO3)3 by a factor of ∼3. It is consistent with the general tendencies of the phosphite anions to act as a weak magnetic mediator, which is caused by the through-bond effect of the P3+ ion in the Fe—O···P3+···O—Fe exchange path, much weaker than in the selenite phase in absence of P3+d contribution. ...}, number={3}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Kovrugin, Vadim M. and Gordon, Elijah E. and Kasapbasi, Esra E. and Whangbo, Myung-Hwan and Colmont, Marie and Siidra, Oleg I. and Colis, Silviu and Krivovichev, Sergey V. and Mentre, Olivier}, year={2016}, month={Jan}, pages={1650–1656} }
 @article{caslin_kremer_razavi_hanfland_syassen_gordon_whangbo_2016, title={Competing Jahn-Teller distortions and hydrostatic pressure effects in the quasi-one-dimensional quantum ferromagnet CuAs2O4}, volume={93}, ISSN={["1550-235X"]}, DOI={10.1103/physrevb.93.022301}, abstractNote={${\mathrm{CuAs}}_{2}{\mathrm{O}}_{4}$ is a $S=1/2$ quasi-one-dimensional ribbon chain compound which orders ferromagnetically at 7.4 K under ambient conditions. ${\mathrm{CuAs}}_{2}{\mathrm{O}}_{4}$ features nearest- and next-nearest-neighbor spin-exchange interactions along the spin chains with a ratio $\ensuremath{\alpha}={J}_{\mathrm{nn}}/{J}_{\mathrm{nnn}}$ in close proximity to the quantum critical point at $\ensuremath{\alpha}=\ensuremath{-}4$. We apply hydrostatic pressure up to $\ensuremath{\sim}11.5$ GPa and examine the structural and magnetic properties using Raman spectroscopy, single-crystal synchrotron x-ray diffraction, and magnetic susceptibility measurements. External pressure severely reduces the axial Jahn-Teller elongations of the oxygen octahedra surrounding the ${\mathrm{Cu}}^{2+}$ cations and stabilizes the ferromagnetic ground state. At 9.2(2) GPa, we detect a structural phase transition leading to an increased twisting of the ${\mathrm{CuO}}_{2}$ ribbon chains and a large drop of the magnetic ordering temperature. Ab initio density functional theory calculations of the spin-exchange parameters, using the structural parameters as a function of pressure, support the experimental findings.}, number={2}, journal={PHYSICAL REVIEW B}, author={Caslin, K. and Kremer, R. K. and Razavi, F. S. and Hanfland, M. and Syassen, K. and Gordon, E. E. and Whangbo, M. -H.}, year={2016}, month={Jan} }
 @article{gordon_kohler_whangbo_2016, title={Condensed-matter equation of states covering a wide region of pressure studied experimentally}, volume={6}, journal={Scientific Reports}, author={Gordon, E. E. and Kohler, J. and Whangbo, M. H.}, year={2016} }
 @article{sen_losey_gordon_argyropoulos_martin_2016, title={Ionic Liquid Character of Zinc Chloride Hydrates Define Solvent Characteristics that Afford the Solubility of Cellulose}, volume={120}, ISSN={1520-6106 1520-5207}, url={http://dx.doi.org/10.1021/acs.jpcb.5b11400}, DOI={10.1021/acs.jpcb.5b11400}, abstractNote={The recently described ionic liquid structure of the three equivalent hydrate of zinc chloride (ZnCl2·R H2O, R = 3, existing as [Zn(OH2)6][ZnCl4]) explains the solubility of cellulose in this medium. Only hydrate compositions in the narrow range of 3 - x < R < 3 + x with x ≈ 1 dissolve cellulose. Once dissolved, the cellulose remains in solution up to the R = 9 hydrate. Neutron diffraction and differential pair distribution function analysis of cellulose and model compound solutions (1 wt % cellulose in the R = 3 hydrate and 1 wt % ethanol in the R = 3 hydrate and the ZnCl2·3 ethanol liquid) coupled with detailed solubility measurements suggest that cellulose solubility occurs via coordination of the primary OH to the hydrated zinc cation with ring hydroxyls forming part of a second coordination shell around the cation of the ionic liquid.}, number={6}, journal={The Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={Sen, Sanghamitra and Losey, Bradley P. and Gordon, Elijah E. and Argyropoulos, Dimitris S. and Martin, James D.}, year={2016}, month={Feb}, pages={1134–1141} }
 @article{gordon_xiang_kohler_whangbo_2016, title={Spin orientations of the spin-half Ir4+ ions in Sr3NiIrO6, Sr2IrO4, and Na2IrO3: Density functional, perturbation theory, and Madelung potential analyses}, volume={144}, number={11}, journal={Journal of Chemical Physics}, author={Gordon, E. E. and Xiang, H. J. and Kohler, J. and Whangbo, M. H.}, year={2016} }
 @article{gordon_xu_xiang_bussmann-holder_kremer_simon_koehler_whangbo_2016, title={Structure and Composition of the 200K-Superconducting Phase of H2S at Ultrahigh Pressure: The Perovskite (SH-)(H3S+)}, volume={55}, ISSN={["1521-3773"]}, DOI={10.1002/anie.201511347}, abstractNote={Abstract}, number={11}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Gordon, Elijah E. and Xu, Ke and Xiang, Hongjun and Bussmann-Holder, Annette and Kremer, Reinhard K. and Simon, Arndt and Koehler, Juergen and Whangbo, Myung-Hwan}, year={2016}, month={Mar}, pages={3682–3684} }
 @misc{whangbo_gordon_xiang_koo_lee_2015, title={Prediction of Spin Orientations in Terms of HOMO-LUMO Interactions Using Spin-Orbit Coupling as Perturbation}, volume={48}, ISSN={["1520-4898"]}, DOI={10.1021/acs.accounts.5b00408}, abstractNote={For most chemists and physicists, electron spin is merely a means needed to satisfy the Pauli principle in electronic structure description. However, the absolute orientations of spins in coordinate space can be crucial in understanding the magnetic properties of materials with unpaired electrons. At low temperature, the spins of a magnetic solid may undergo long-range magnetic ordering, which allows one to determine the directions and magnitudes of spin moments by neutron diffraction refinements. The preferred spin orientation of a magnetic ion can be predicted on the basis of density functional theory (DFT) calculations including electron correlation and spin-orbit coupling (SOC). However, most chemists and physicists are unaware of how the observed and/or calculated spin orientations are related to the local electronic structures of the magnetic ions. This is true even for most crystallographers who determine the directions and magnitudes of spin moments because, for them, they are merely the parameters needed for the diffraction refinements. The objective of this article is to provide a conceptual framework of thinking about and predicting the preferred spin orientation of a magnetic ion by examining the relationship between the spin orientation and the local electronic structure of the ion. In general, a magnetic ion M (i.e., an ion possessing unpaired spins) in a solid or a molecule is surrounded with main-group ligand atoms L to form an MLn polyhedron, where n is typically 4-6, and the d states of MLn are split because the antibonding interactions of the metal d orbitals with the p orbitals of the surrounding ligands L depend on the symmetries of the orbitals involved.1 The magnetic ion M of MLn has a certain preferred spin direction because its split d states interact among themselves under SOC.2,3 The preferred spin direction can be readily predicted on the basis of perturbation theory in which the SOC is taken as perturbation and the split d states as unperturbed states by inspecting the magnetic quantum numbers of its d orbitals present in the HOMO and LUMO of the MLn polyhedron. This is quite analogous to how chemists predict whether a chemical reaction is symmetry-allowed or symmetry-forbidden in terms of the HOMO-LUMO interactions by simply inspecting the symmetries of the frontier orbitals.4,5 Experimentally, the determination of the preferred spin orientations of magnetic ions requires a sophisticated level of experiments, for example, neutron diffraction measurements for magnetic solids with an ordered spin state at a very low temperature. Theoretically, it requires an elaborate level of electronic structure calculations, namely, DFT calculations including electron correlation and SOC. We show that the outcomes of such intricate experimental measurements and theoretical calculations can be predicted by a simple perturbation theory analysis.}, number={12}, journal={ACCOUNTS OF CHEMICAL RESEARCH}, author={Whangbo, Myung-Hwan and Gordon, Elijah E. and Xiang, Hongjun and Koo, Hyun-Joo and Lee, Changhoon}, year={2015}, month={Dec}, pages={3080–3087} }
 @article{canevet_fak_kremer_chun_enderle_gordon_bettis_whangbo_taylor_adroja_2015, title={Spin excitations in the two-dimensional strongly coupled dimer system malachite}, volume={91}, ISSN={["1550-235X"]}, DOI={10.1103/physrevb.91.060402}, abstractNote={The mineral malachite, Cu2(OD)2CO3, has a quantum spin-liquid ground state and no long-range magnetic order down to at least T=0.4 K. Inelastic neutron scattering measurements show that the excitation spectrum consists of dispersive gapped singlet-triplet excitations, characteristic of spin-1/2 dimer-forming Heisenberg antiferromagnets. We identify a new two-dimensional dimerized coupling scheme with strong interdimer coupling J'/J1~0.3 that places malachite between strongly coupled alternating chains, square lattice antiferromagnets, and infinite-legged ladders. The geometry of the interaction scheme resembles the staggered dimer lattice, which may allow unconventional quantum criticality.}, number={6}, journal={PHYSICAL REVIEW B}, author={Canevet, E. and Fak, B. and Kremer, R. K. and Chun, J. H. and Enderle, M. and Gordon, E. E. and Bettis, J. L. and Whangbo, M. -H. and Taylor, J. W. and Adroja, D. T.}, year={2015}, month={Feb} }
 @article{read_gordon_smith_yeon_morrison_whangbo_loye_2015, title={Synthesis of the Layered Quaternary Uranium-Containing Oxide Cs2Mn3U6O22 and Characterization of its Magnetic Properties}, volume={54}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.5b00552}, abstractNote={A layered quaternary uranium-containing oxide, Cs2Mn3U6O22, was crystallized from a cesium chloride flux. The crystal structure was determined to consist of α-U3O8 topological layers that are separated by alternating cesium and manganese layers. This ordered arrangement creates a separation between manganese layers of 13 Å, leading to complex low-dimensional magnetic properties. The compound crystallizes in a new structure type in the monoclinic space group, C2/m, with a = 6.8730(10) Å, b = 11.7717(17) Å, c = 13.374(2) Å, and β = 99.673(5)°. The magnetic properties were measured and analyzed by first-principles density functional theory calculations.}, number={11}, journal={INORGANIC CHEMISTRY}, author={Read, Cory M. and Gordon, Elijah E. and Smith, Mark D. and Yeon, Jeongho and Morrison, Gregory and Whangbo, Myung-Hwan and Loye, Hans-Conrad}, year={2015}, month={Jun}, pages={5495–5503} }
 @article{whangbo_gordon_bettis_bussmann-holder_koehler_2015, title={Tolerance Factor and Cation-Anion Orbital Interactions Differentiating the Polar and Antiferrodistortive Structures of Perovskite Oxides ABO(3)}, volume={641}, ISSN={["1521-3749"]}, DOI={10.1002/zaac.201500058}, abstractNote={Abstract}, number={6}, journal={ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE}, author={Whangbo, Myung-Hwan and Gordon, Elijah E. and Bettis, Jerry L., Jr. and Bussmann-Holder, Annette and Koehler, Juergen}, year={2015}, month={May}, pages={1043–1052} }