Magnetic frustration in BaCuSi2O6 released

Han Purple (BaCuSi2O6) is not only an ancient pigment, but also a valuable model material for studying Bose-Einstein condensation (BEC) of magnons in high magnetic fields. Using precise low-temperature structural data and extensive density-functional calculations, we elucidate magnetic couplings in this compound. The resulting magnetic model comprises two types of nonequivalent spin dimers, in excellent agreement with the (63,65)Cu nuclear magnetic resonance data. We further argue that leading interdimer couplings connect the upper site of one dimer to the bottom site of the contiguous dimer, and not the upper-to-upper and bottom-to-bottom sites, as assumed previously. This finding is verified by inelastic neutron scattering data and implies the lack of magnetic frustration in BaCuSi2O6, thus challenging existing theories of the magnon BEC in this compound.Comment: 4.5 pages, 4 figures, 1 tabl

Behavior of nanocomposite consisting of manganese ferrite particles and atomic layer deposited bismuth oxide chloride film

Nanocomposites of manganese ferrite and bismuth oxide chloride were synthesized. The composites consisted of 10 nm thick nanocrystalline bismuth oxide chloride thin film grown by atomic layer deposition on spinel MnFe2O4 nanoparticles prepared by wet chemical synthesis. The composite layers exhibited nonlinear polarization behavior in both magnetic and electric fields at room temperature. The magnetic coercive force, HC, was 30 – 40 Oe at room temperature. The width of electrical charge – voltage hysteresis loop reached 3.6 MV/cm.Peer reviewe

Electric and Magnetic Properties of Atomic Layer Deposited ZrO2-HfO2 Thin Films

Atomic layer deposition method was employed to deposit thin films consisting of ZrO2 and HfO2. Zirconia films were doped with hafnia and vice versa, and also nanolaminates were formed. All depositions were carried out at 300 degrees C. Most films were crystalline in their as-deposited state. Zirconia exhibited the metastable cubic and tetragonal phases by a large majority, whereas hafnia was mostly in its stable monoclinic phase. Magnetic and electrical properties of the films were assessed. Un-doped zirconia was ferromagnetic and this property diminished with increasing the amount of hafnia in a film. All films exhibited ferroelectric-like behavior and the polarization curves also changed with respect to the film composition. (C) The Author(s) 2018. Published by ECS.Peer reviewe

Magnetic and Electrical Performance of Atomic Layer Deposited Iron Erbium Oxide Thin Films

Mixed films of a high-permittivity oxide, Er2O3, and a magnetic material, Fe2O3, were grown by atomic layer deposition on silicon and titanium nitride at 375 degrees C using erbium diketonate, ferrocene, and ozone as precursors. Crystalline phases of erbium and iron oxides were formed. Growth into three-dimensional trenched structures was demonstrated. A structure deposited using tens to hundreds subsequent cycles for both constituent metal oxide layers promoted both charge polarization and saturative magnetization compared to those in the more homogeneously mixed films.Peer reviewe

Properties of Atomic Layer Deposited Nanolaminates of Zirconium and Cobalt Oxides

Five-layer crystalline thin film structures were formed, consisting of ZrO2 and Co3O4 alternately grown on Si(100) substrates by atomic layer deposition at 300 degrees C using ZrCl4 and Co(acac)(3) as the metal precursors and ozone as the oxygen precursor. The performance of the laminate films was dependent on the relative content of constituent oxide layers. The magnetization in these films was nonlinear, saturative, and with very weak coercive fields. Electrical measurements revealed the formation of significant polarization versus external field loops and implied some tendency toward memristive behavior. (C) The Author(s) 2018. Published by ECS.Peer reviewe

Atomic Layer Deposition and Performance of ZrO2-Al2O3 Thin Films

Thin mixed and nanolaminate films of ZrO2 and Al2O3 were grown by atomic layer deposition from the corresponding metal chlorides and water. The films were grown at 350 degrees C in order to ensure ZrO2 crystallization in the as-deposited state. The relative thicknesses of layers in the structure of the nanolaminates were controlled in order to maximize the content of metastable polymorphs of ZrO2 that have higher permittivity than that of the stable monoclinic ZrO2 . The multilayer films demonstrated interfacial charge polarization and saturative magnetization in external fields. The conductivity of the films could be switched between high and low resistance states by applying voltages of alternating polarity. (C) 2018 The Electrochemical Society.Peer reviewe