Browsing by Author "Weiland, Ashley"
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Item Law and Disorder: Special Stacking Units—Building the Intergrowth Ce₆ Co₅ Ge₁₆(American Chemical Society, 2019-04-22) Felder, Justin B.; Weiland, Ashley; Hodovanets, H.; McCandless, George T.; Estrada, Tania G.; Martin, Thomas J.; Walker, Amy V.; Paglione, J.; Chan, Julia Y.; 0000-0003-4434-2160 (Chan, JY); 0000-0002-2528-1967 (Felder, JB); 0000-0001-7198-3559 (Weiland, A); 0000-0003-2114-3644 (Walker, AV); Felder, Justin B.; Weiland, Ashley; McCandless, George T.; Estrada, Tania G.; Martin, Thomas J.; Walker, Amy V.; Chan, Julia Y.A new structure type of composition Ce₆ Co₅ Ge₁₆ was grown out of a molten Sn flux. Ce₆ Co₅ Ge₁₆ crystallizes in the orthorhombic space group Cmcm, with highly anisotropic lattice parameters of α = 4.3293(5) Å, b = 55.438(8) Å, and c = 4.3104(4) Å. The resulting single crystals were characterized by X-ray diffraction, and the magnetic and transport properties are presented. The Sn-stabilized structure of Ce₆ Co₅ Ge₁₆ is based on the stacking of disordered Ce cuboctahedra and is an intergrowth of existing structure types including AlB₂ , BaNiSn₃, and AuCu₃. The stacking of structural subunits has previously been shown to be significant in the fields of superconductivity, quantum materials, and optical materials. Herein, we present the synthesis, characterization, and complex magnetic behavior of Ce₆ Co₅ Ge₁₆ at low temperature, including three distinct magnetic transitions. © 2019 American Chemical Society.Item Synthetic Design of Cerium-Based Intermetallics(2021-05-01T05:00:00.000Z) Weiland, Ashley; Chan, Julia; Xuan, Zhenyu; Zheng, Jie; Nielsen, Steven O.; Walker, Amy V.Ce-based highly correlated systems are of interest due to Ce3+ (S=1/2) providing an ideal f-electron system to study the interplay of localized magnetic moments and conduction electrons. The growth of high-quality single crystals is of utmost importance to ensure the determination of intrinsic anisotropic properties. This dissertation presents the single crystal growth and d etailed characterization of Ce-containing intermetallics. Motivated by the search for new spintronic devices based on topological materials, the first study highlights the incorporation of Bi in the topological parent compound, CeSbTe. Sb net containing CeSbTe has been studied to show the interplay of magnetism and topology. Inserting Bi, a larger element, provides the opportunity to change the Fermi surface while preserving topologically relevant features. We show the band structure engineering of potential topological materials LnSb1-xBixTe (Ln = La, Ce, Pr; x ~ 0.2) and CeBiTe. Continuing our search for novel quantum materials, our elucidation of crystal growth parameters of Ce-based intermetallics, led to the identification of a new intermetallic homologous series An+1MnX3n+1 (A = rare earth; M = transition metal; X = tetrels; n = 1 – 6) built up of structural subunits such as AlB2, AuCu3, and BaNiSn3. The homologous series serves as a model system for studying the coupling between localized f-electrons and conduction electrons. Additionally, the stacking of heterostructural subunits is an exciting way to modify physical properties of related phases, highlighting the importance of structural building blocks as a new avenue to study magnetism and topology. Crystal growth, detailed single crystal structural modeling, and magnetic and transport properties of Ce5Co4+xGe13-ySny (n = 4), Ce6Co5+xGe16-ySny (n = 5), and Ce7Co6+xGe19-ySny (n = 6), are presented. The similarities between the synthetic profiles used to grow n = 4 – 6 brought about new questions which led to our work investigating phase formation. Finally, the process for designing in situ synchrotron experiments, including a new sample environment and furnace apparatus for the use with flux grown intermetallics, is presented.Item The Role of Crystal Growth Conditions on the Magnetic Properties of Ln₂Fe₄₋ₓCoₓSb₅ (Ln = La and Ce)(American Chemical Society, 2019-04-15) Weiland, Ashley; Li, Sheng; Benavides, Katherine A.; Burnett, Joseph V.; Milam-Guerrero, J.; Neer, Abbey J.; McCandless, Gregory T.; Lv, Bing; Chan, Julia Y.; 0000-0001-7198-3559 (Weiland, A); 0000-0002-9491-5177 (Lv, B); 0000-0003-4434-2160 (Chan, JY); Weiland, Ashley; Li, Sheng; Benavides, Katherine A.; Burnett, Joseph V.; Neer, Abbey J.; McCandless, Gregory T.; Lv, Bing; Chan, Julia Y.Single crystals of Ln₂Fe₄₋ₓCoₓSb_{5-y}Bi_y (Ln = La, Ce; 0 ≤ x ≤ 0.5; 0 ≤ y ≤ 0.2) were grown using Bi flux and self-flux methods. The compounds adopt the La₂Fe₄Sb₅ structure type with tetragonal space group I4/mmm. The La₂Fe₄Sb₅ structure type is comprised of rare earth atoms capping square Sb nets in a square antiprismatic fashion and two transition-metal networks forming a PbO-type layer with Sb and transition-metal isosceles triangles. Substituting Co into the transition-metal sublattice results in a decrease in the transition temperature and reduced frustration, indicative of a transition from localized to itinerant behavior. In this manuscript, we demonstrated that Bi can be used as an alternate flux to grow single crystals of antimonides. Even with the incorporation of Bi into the Sb square net, the magnetic properties are not significantly affected. In addition, we have shown that the incorporation of Co into the Fe triangular sublattice leads to an itinerant magnetic system. ©2019 American Chemical Society.