5 research outputs found
Thin Film Growth of Black Phosphorus and Black Arsenic Phosphorus
University of Minnesota Ph.D. dissertation. 2020. Major: Material Science and Engineering. Advisors: Stephen Campbell, Dan Frisbie. 1 computer file (PDF); 147 pages.A single-step, direct silicon-substrate growth of black phosphorus (b-P) thin films is achieved by a self-contained (ampule) short-way transport method. The synthesis reactants include tin (Sn), tin tetraiodide (SnI4), and red phosphorus (r-P). A self-generated low-pressure condition of 102. Thin film b-ASP FET’s fabricated from exfoliated bulk-b-AsP grown in the same conditions as the thin film growth process show an on-off current ratio of 102, a threshold voltage of -60 V, and a peak field-effect hole mobility of 23 cm2/V·s at Vd=-0.9 and Vg=-60 V
NH<sub>4</sub>FeCl<sub>2</sub>(HCOO): Synthesis, Structure, and Magnetism of a Novel Low-Dimensional Magnetic Material
Solvothermal
synthesis was used to create a low-dimensional ironÂ(II)
chloride formate compound, NH<sub>4</sub>FeCl<sub>2</sub>Â(HCOO),
that exhibits interesting magnetic properties. NH<sub>4</sub>FeCl<sub>2</sub>Â(HCOO) crystallizes in the monoclinic space group <i>C</i>2/<i>c</i> (No. 15) with <i>a</i> =
7.888(1) Å, <i>b</i> = 11.156(2) Å, <i>c</i> = 6.920(2) Å, and β = 108.066(2)°. The crystal structure
consists of infinite zigzag chains of distorted Fe<sup>2+</sup>-centered
octahedra linked by μ<sub>2</sub>-Cl and syn-syn formate bridges,
with interchain hydrogen bonding through NH<sub>4</sub><sup>+</sup> cations holding the chains together. The unique Fe<sup>2+</sup> site
is coordinated by four equatorial chlorides at a distance of 2.50
Ã… and two axial oxygens at a distance of 2.08 Ã…. Magnetic
measurements performed on powder and oriented single-crystal samples
show complex anisotropic magnetic behavior dominated by antiferromagnetic
interactions (<i>T</i><sub>N</sub> = 6 K) with a small ferromagnetic
component in the direction of chain propagation. An anisotropic metamagnetic
transition was observed in the ordered state at 2 K in an applied
magnetic field of 0.85–3 T. <sup>57</sup>Fe Mössbauer
spectroscopy reveals mixed hyperfine interactions below the ordering
temperature, with strong electric field gradients and complex noncollinear
arrangement of the magnetic moments
A Series of Chiral, Polar, Homospin Topological Ferrimagnets: M<sub>3</sub>(OOCH)<sub>5</sub>Cl(OH<sub>2</sub>) (M = Fe, Co, Ni)
An isostructural
series of transition metal-formate-chloride-hydrate
compounds, M<sub>3</sub>(OOCH)<sub>5</sub>ClÂ(OH<sub>2</sub>) (M =
Fe, Co, Ni), have been synthesized using a solvothermal method. These
compounds crystallize in the chiral and polar space group <i>P</i>3<sub>1</sub> and are comprised of three different types
of helical chains of edge-sharing M<sup>2+</sup>-centered octahedra.
All three compounds undergo 3D ferrimagnetic ordering at low temperature,
and the iron and cobalt analogues exhibit field-induced metamagnetic
transitions. The magnetic structure was determined by neutron powder
diffraction, revealing ferromagnetic intrachain coupling and antiferromagnetic
interchain interactions, with the three chains arranged in a two-up/one-down
triangular lattice. As all three chains contain one type of metal
in the same spin state, these compounds are rare examples of homospin
topological ferrimagnets
A Series of Chiral, Polar, Homospin Topological Ferrimagnets: M<sub>3</sub>(OOCH)<sub>5</sub>Cl(OH<sub>2</sub>) (M = Fe, Co, Ni)
An isostructural
series of transition metal-formate-chloride-hydrate
compounds, M<sub>3</sub>(OOCH)<sub>5</sub>ClÂ(OH<sub>2</sub>) (M =
Fe, Co, Ni), have been synthesized using a solvothermal method. These
compounds crystallize in the chiral and polar space group <i>P</i>3<sub>1</sub> and are comprised of three different types
of helical chains of edge-sharing M<sup>2+</sup>-centered octahedra.
All three compounds undergo 3D ferrimagnetic ordering at low temperature,
and the iron and cobalt analogues exhibit field-induced metamagnetic
transitions. The magnetic structure was determined by neutron powder
diffraction, revealing ferromagnetic intrachain coupling and antiferromagnetic
interchain interactions, with the three chains arranged in a two-up/one-down
triangular lattice. As all three chains contain one type of metal
in the same spin state, these compounds are rare examples of homospin
topological ferrimagnets