Vasile O. Garlea

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We demonstrate that the action of physical pressure, chemical compression, or aliovalent substitution in ACo2As2 (A = Eu and Ca) has a general consequence of causing these antiferromagnetic materials to become ferromagnets. In all cases, the mixed valence triggered at the electropositive A site results in the increase of the Co 3d density of states at the(More)
The metal-insulator transition (MIT) is one of the most dramatic manifestations of electron correlations in materials. Various mechanisms producing MITs have been extensively considered, including the Mott (electron localization via Coulomb repulsion), Anderson (localization via disorder), and Peierls (localization via distortion of a periodic(More)
Temperature dependencies of gap energies and magnon lifetimes are measured in the quasi-one-dimensional S=1/2 gapped quantum magnets (CH3)(2)CHNH(3)CuCL(3) (IPA-CuCl(3), where IPA denotes isopropyl ammonium) and Cu(2)Cl(4).D(8)C(4)SO(2) (Sul-Cu(2)Cl(4)) using inelastic neutron scattering. The results are compared to those found in literature for S=1 Haldane(More)
Ten compounds belonging to the series of oxygen-deficient perovskite oxides Ca(2)Fe(2-x)Mn(x)O(5) and CaSrFe(2-x)Mn(x)O(5+y), where x = 1/2, 2/3, and 1 and y ≈ 0-0.5, were synthesized and investigated with respect to the ordering of oxygen vacancies on both local and long-range length scales and the effect on crystal structure and magnetic properties. For(More)
The attractive/repulsive relationship between superconductivity and magnetic ordering has fascinated the condensed matter physics community for a century. In the early days, magnetic impurities doped into a superconductor were found to quickly suppress superconductivity. Later, a variety of systems, such as cuprates, heavy fermions, and Fe pnictides, showed(More)
The crystal structures of two Delafossites, Cu3Ni2SbO6 and Cu3Co2SbO6, are determined by high-resolution synchrotron powder X-ray diffraction. The Ni and Co are ordered with respect to Sb in the layer of edge sharing octahedra, forming magnetic layers with honeycomb geometry. High-resolution electron microscopy confirms ordering, and selected-area electron(More)
Neutron inelastic scattering and diffraction techniques have been used to study the MnV2O4 spinel system. Our measurements show the existence of two transitions to long-range ordered ferrimagnetic states, the first collinear and the second noncollinear. The lower temperature transition, characterized by development of antiferromagnetic components in the(More)
New BaMnPnF (Pn = As, Sb, Bi) are synthesized by stoichiometric reaction of elements with BaF₂. They crystallize in the P4/nmm space group, with the ZrCuSiAs-type structure, as indicated by X-ray crystallography. Electrical resistivity results indicate that Pn = As, Sb, and Bi are semiconductors with band gaps of 0.73 eV, 0.48 eV and 0.003 eV (extrinsic(More)
V. O. Garlea,1,* J. L. Zarestky,1 C. Y. Jones,2 L.-L. Lin,1 D. L. Schlagel,3 T. A. Lograsso,3 A. O. Tsokol,3 V. K. Pecharsky,3,4 K. A. Gschneidner, Jr.,3,4 and C. Stassis1 1Ames Laboratory and Department of Physics, Iowa State University, Ames, Iowa 50011, USA 2National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA 3Materials and(More)
Aifeng Wang ( ),1 I. Zaliznyak,1 Weijun Ren ( ),1,2 Lijun Wu,1 D. Graf,3 V. O. Garlea,4 J. B. Warren,5 E. Bozin,1 Yimei Zhu,1 and C. Petrovic1 1Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA 2Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy(More)