Browsing by Author "Chan, Julia Y."
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Item Bulk Fermi Surface of The Weyl Type-II Semimetallic Candidate NbIrTe₄(American Physical Society, 2019-05-15) Schönemann, R.; Chiu, Y. -C; Zheng, W.; Quito, V. L.; Sur, S.; McCandless, Gregory T.; Chan, Julia Y.; Balicas, L.; 0000-0003-4434-2160 (Chan, JY); McCandless, Gregory T.; Chan, Julia Y.Recently, a new group of layered transition-metal tetra-chalcogenides was proposed via first-principles calculations to correspond to a new family of Weyl type-II semimetals with promising topological properties in the bulk as well as in the monolayer limit. In this paper, we present measurements of the Shubnikov-de Haas (SdH) and de Haas-van Alphen effects under high magnetic fields for the type-II Weyl semimetallic candidate NbIrTe₄. We find that the angular dependence of the observed Fermi surface extremal cross-sectional areas agree well with our density functional theory (DFT) calculations supporting the existence of Weyl type-II points in this material. Although we observe a large and nonsaturating magnetoresistivity in NbIrTe4 under fields all the way up to 35T, Hall-effect measurements indicate that NbIrTe₄ is not a compensated semimetal. The transverse magnetoresistivity displays a fourfold angular dependence akin to the so-called butterfly magnetoresistivity observed in nodal line semimetals. We conclude that the magnetoresistivity and its unconventional angular dependence are governed by the topography of the Fermi surface and the resulting anisotropy in effective masses and in carrier mobilities. © 2019 American Physical Society.Item Detailed Study of the Fermi Surfaces of the Type-II Dirac Semimetallic Candidates XTe₂ (X =Pd, Pt)(American Physical Society) Zheng, W.; Schönemann, R.; Aryal, N.; Zhou, Q.; Rhodes, D.; Chiu, Y. -C; Chen, K. -W; Kampert, E.; Förster, T.; Martin, T. J.; McCandless, Gregory T.; Chan, Julia Y.; Manousakis, E.; Balicas, L.; 0000-0003-4434-2160 (Chan, JY); Martin, T. J.; McCandless, Gregory T.; Chan, Julia Y.We present a detailed quantum oscillatory study on the Dirac type-II semimetallic candidates PdTe₂ and PtTe₂ via the temperature and the angular dependence of the de Haas-van Alphen and Shubnikov-de Haas effects. In high-quality single crystals of both compounds, i.e., displaying carrier mobilities between 10³ and 10⁴ cm²/Vs, we observed a large nonsaturating magnetoresistivity which in PtTe₂ at a temperature T=1.3 K leads to an increase in the resistivity up to (5×10⁴)% under a magnetic field μ₀H=62 T. These high mobilities correlate with their light effective masses in the range of 0.04 to 1 bare electron mass according to our measurements. For PdTe₂ the experimentally determined Fermi surface cross-sectional areas show excellent agreement with those resulting from band structure calculations. Surprisingly, this is not the case for PtTe₂, whose agreement between calculations and experiments is relatively poor even when electronic correlations are included in the calculations. Therefore, our study provides strong support for the existence of a Dirac type-II node in PdTe₂ and probably also for PtTe₂. Band structure calculations indicate that the topologically nontrivial bands of PtTe₂ do not cross the Fermi level. In contrast, for PdTe₂ the Dirac type-II cone does intersect, although our calculations also indicate that the associated cyclotron orbit on the Fermi surface is located in a distinct k_z plane with respect to that of the Dirac type-II node. Therefore, it should yield a trivial Berry phase.Item Effects of Hydrostatic Pressure on Magnetostructural Transitions and Magnetocaloric Properties in (MnNiSi)₁₋ₓ (FeCoGe)ₓ(Amer Inst Physics, 2015-03-26) Samanta, Tapas; Lepkowski, Daniel L.; Saleheen, Ahmad Us; Shankar, Alok; Prestigiacomo, Joseph; Dubenko, Igor; Quetz, Abdiel; Oswald, Iain W. H.; McCandless, Gregory T.; Chan, Julia Y.; Adams, Philip W.; Young, David P.; Ali, Naushad; Stadler, ShaneThe isostructural alloying of two compounds with different magnetic and thermo-structural properties has resulted in a new system, (MnNiSi)(1-x)(FeCoGe)(x), that exhibits large magnetocaloric effects with acute sensitivity to both compositional variation and applied hydrostatic pressure. The maximum isothermal entropy change reaches a value of -Delta S-max - 143.7 J/kg K for a field change of Delta B - 5 T at atmospheric pressure. The first-order magnetostructural transition responsible for the entropy change shifts to lower temperature with applied hydrostatic pressure (similar to-10 K/kbar) but maintains a large value of -Delta S-max.Item Emerging Investigators in Solid-State Inorganic Chemistry(Amer Chemical Soc, 2018-12-10) Latturner, Susan E.; Chan, Julia Y.; 0000-0003-4434-2160 (Chan, JY); Chan, Julia Y.No abstract available.Item Fermi Surface of the Weyl Type-II Metallic Candidate WP₂(2018-09-12) Schönemann, R.; Aryal, N.; Zhou, Q.; Chiu, Y. -C; Chen, K. -W; Martin, T. J.; McCandless, G. T.; Chan, Julia Y.; Manousakis, E.; Balicas, L.; Martin, T. J.; McCandless, G. T.; Chan, Julia Y.Weyl type-II fermions are massless quasiparticles that obey the Weyl equation and which are predicted to occur at the boundary between electron and hole pockets in certain semimetals, i.e., the (W,Mo)(Te₁,P)₂ compounds. Here, we present a study of the Fermi surface of WP₂ via the Shubnikov-de Haas (SdH) effect. Compared to other semimetals, WP₂ exhibits a very low residual resistivity, i.e., ρ₀≃10 nΩ cm, which leads to perhaps the largest nonsaturating magnetoresistivity [ρ(H)] reported for any compound. For the samples displaying the smallest ρ₀, ρ(H) is observed to increase by a factor of 2.5×10⁷% under μ₀H=35 T at T=0.35 K. The angular dependence of the SdH frequencies is found to be in excellent agreement with the first-principles calculations when the electron and hole bands are shifted by 30 meV with respect to the Fermi level. This small discrepancy could have implications for the predicted topological character of this compound.Item Ferromagnetic Ordering Along the Hard Axis in the Kondo Lattice YbIr₃Ge₇(American Physical Society) Rai, B. K.; Stavinoha, M.; Banda, J.; Hafner, D.; Benavides, Katherine A.; Sokolov, D. A.; Chan, Julia Y.; Brando, M.; Huang, C. -L; Morosan, E.; Benavides, Katherine A.; Chan, Julia Y.Ferromagnetic Kondo lattice compounds are far less common than their antiferromagnetic analogs. In this Rapid Communication, we report the discovery of a ferromagnetic Kondo lattice compound, YbIr₃Ge₇. As in almost all ferromagnetic Kondo lattice systems, YbIr₃Ge₇ shows magnetic order with moments aligned orthogonal to the crystal electric field (CEF) easy axis. YbIr₃Ge₇ is unique in that it is the only member of this class of compounds that crystallizes in a rhombohedral structure with a trigonal point symmetry of the magnetic site, and it lacks broken inversion symmetry at the local moment site. The ac magnetic susceptibility, magnetization, and specific heat measurements show that YbIr₃Ge₇ has a Kondo temperature TK≈14 K and a Curie temperature T_{C}=2.4K. Ferromagnetic order occurs along the crystallographic [100] hard CEF axis despite the large CEF anisotropy of the ground-state Kramers doublet with a saturation moment along [001] almost four times larger than the one along [100]. This implies that a mechanism which considers the anisotropy in the exchange interaction to explain the hard-axis ordering is unlikely. On the other hand, the broad second-order phase transition at T_{C} favors a fluctuation-induced mechanism. © 2019 American Physical Society.Item Hydrostatic Pressure-Induced Modifications of Structural Transitions Lead to Large Enhancements of Magnetocaloric Effects in MnNiSi-Based Systems(Amer Physical Soc, 2015-01-05) Samanta, Tapas; Lepkowski, Daniel L.; Saleheen, Ahmad Us; Shankar, Alok; Prestigiacomo, Joseph; Dubenko, Igor; Quetz, Abdiel; Oswald, Iain W. H.; McCandless, Gregory T.; Chan, Julia Y.; Adams, Philip W.; Young, David P.; Ali, Naushad; Stadler, ShaneA remarkable decrease of the structural transition temperature of MnNiSi from 1200 to < 300 K by chemically alloying it with MnFeGe results in a coupling of the magnetic and structural transitions, leading to a large magnetocaloric effect near room temperature. Application of relatively low hydrostatic pressures (similar to 2.4 kbar) lead to an extraordinary enhancement of the isothermal entropy change from -Delta S = 44 to 89 J/kgK at ambient and 2.4 kbar applied pressures, respectively, for a field change of Delta B = 5 T, and is associated with a large relative volume change of about 7% with P = 2.4 kbar.Item Intermediate Valence to Heavy Fermion Through a Quantum Phase Transition in Yb₃(Rh₁₋xTx)₄ Ge₁₃ (T = Co, Ir) Single Crystals(Amer Physical Soc, 2016-01-04) Rai, Binod K.; Oswald, Iain W. H.; Chan, Julia Y.; Morosan, E.; Oswald, Iain W. H.; Chan, Julia Y.Single crystals of Yb₃(Rh₁₋xTx)₄ Ge₁₃ (T = Co, Ir) have been grown using the self-flux method. Powder x-ray diffraction data on these compounds are consistent with the cubic structure with space group Pm3̅n. Intermediate-valence behavior is observed in Yb₃(Rh₁₋xTx)₄ Ge₁₃ upon T = Co doping, while T = Ir doping drives the system into a heavy-fermion state. Antiferromagnetic order is observed in the Ir-doped samples Yb₃(Rh₁₋xTx)₄ Ge₁₃ for 0.5 < x ≤ 1 with T_N = 0.96 K for Yb₃Ir₄Ge₁₃. With decreasing x, the magnetic order is suppressed towards a quantum critical point around x_c = 0.5, accompanied by non-Fermi-liquid behavior evidenced by logarithmic divergence of the specific heat and linear temperature dependence of the resistivity. The Fermi-liquid behavior is recovered with the application of large magnetic fields.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 Magnetic, Thermodynamic, and Electrical Transport Properties of the Noncentrosymmetric B20 Germanides MnGe and CoGe(American Physical Society, 2014-10-03) Ditusa, J. F.; Zhang, S. B.; Yamaura, K.; Xiong, Y.; Prestigiacomo, J. C.; Fulfer, B. W.; Adams, P. W.; Brickson, M. I.; Browne, D. A.; Capan, C.; Fisk, Z.; Chan, Julia Y.; C-5392-2008 (Chan, JY)We present magnetization, specific heat, resistivity, and Hall effect measurements on the cubic B20 phase of MnGe and CoGe and compare to measurements of isostructural FeGe and electronic-structure calculations. In MnGe, we observe a transition to a magnetic state at Tc=275K as identified by a sharp peak in the ac magnetic susceptibility, as well as second phase transition at lower temperature that becomes apparent only at finite magnetic field. We discover two phase transitions in the specific heat at temperatures much below the Curie temperature, one of which we associate with changes to the magnetic structure. A magnetic field reduces the temperature of this transition which corresponds closely to the sharp peak observed in the ac susceptibility at fields above 5 kOe. The second of these transitions is not affected by the application of field and has no signature in the magnetic properties or our crystal-structure parameters. Transport measurements indicate that MnGe is metallic with a negative magnetoresistance similar to that seen in isostructural FeGe and MnSi. Hall effect measurements reveal a carrier concentration of about 0.5 carriers per formula unit, also similar to that found in FeGe and MnSi. CoGe is shown to be a low carrier density metal with a very small, nearly temperature-independent diamagnetic susceptibility.Item Observation of a Two-Dimensional Fermi Surface and Dirac Dispersion in YbMnSb₂(Amer Physical Soc, 2018-10-22) Kealhofer, Robert; Jang, Sooyoung; Griffin, Sinead M.; John, Caolan; Benavides, Katherine A.; Doyle, Spencer; Helm, T.; Moll, Philip J. W.; Neaton, Jeffrey B.; Chan, Julia Y.; Denlinger, J. D.; Analytis, James G.; 0000-0003-4434-2160 (Chan, JY); Benavides, Katherine A.; Chan, Julia Y.We present the crystal structure, electronic structure, and transport properties of the material YbMnSb₂, a candidate system for the investigation of Dirac physics in the presence of magnetic order. Our measurements reveal that this system is a low-carrier-density semimetal with a two-dimensional Fermi surface arising from a Dirac dispersion, consistent with the predictions of density-functional-theory calculations of the antiferromagnetic system. The low temperature resistivity is very large, suggesting that scattering in this system is highly efficient at dissipating momentum despite its Dirac-like nature.Item One-Dimensional Tellurium Chains: Crystal Structure and Thermodynamic Properties of PrCuₓTe₂ (x ~ 0.45)(Elsevier Inc., 2018-10-20) Baumbach, Ryan; Balicas, Luis; McCandless, Gregory T.; Sotelo, Paola; Zhang, Qiu R.; Evans, Jess; Camdzic, Dino; Martin, Thomas J.; Chan, Julia Y.; Macaluso, Robin T.; 0000-0003-4434-2160 (Chan, JY); McCandless, Gregory T.; Martin, Thomas J.; Chan, Julia Y.X-ray diffraction, crystal structure, magnetization, and heat capacity results are presented for the rare earth chalcogenide ternary system PrCu₀.₄₅Te₂ and its non-4⨍ analogue LaCu₀.₄₀Te₂. The crystal structure of PrCu₀.₄₅Te₂ is characterized by chains of edge and corner-sharing CuTe₄ tetrahedra and Pr centered in polyhedra comprised of Cu and Te. The Cu site is partially occupied and exhibits signatures of local disorder. Magnetic susceptibility measurements show a Curie-Weiss temperature dependence consistent with a Pr³⁺ state. No magnetic ordering is observed down to 1.8 K, but the negative Curie-Weiss temperature suggests an antiferromagnetic exchange interaction. Importantly, the low temperature heat capacity of PrCu₀.₄₅Te₂ is strongly enhanced by comparison to LaCu₀.₄₀Te₂, suggesting that there is a build-up of entropy that is associated with the 4f-electrons from the Pr³⁺ ions. These features reveal possible spin frustration behavior and introduce this family of materials as a template for studying new phenomenon.Item The Proof Is in the Powder: Revealing Structural Peculiarities in the Yb₃Rh₄Sn₁₃ Structure Type(Royal Soc Chemistry, 2018-09-12) Oswald, Iain W. H.; Rai, Binod K.; McCandless, Gregory T.; Morosan, Emilia; Chan, Julia Y.; 0000-0003-4434-2160 (Chan, JY); Oswald, Iain W. H.; Rai, Binod K.; McCandless, Gregory T.; Morosan, Emilia; Chan, Julia Y.Compounds adopting the Yb₃Rh₄Sn₁₃ structure type have drawn attention because of the revelation of exotic states such as heavy fermion behavior, superconductivity, charge density wave, and quantum critical behavior. The prototypical structure has historically been modeled with a primitive cubic space group, Pm3̅n; however, structural studies have led to the realization of disordered atomic sites, requiring lower symmetry models. We will review the low symmetry models required to describe the structural distortions in the related Yb₃Rh₄Sn₁₃ structure type. In addition, we present the structure determination of a new analogue, Lu₃Ir₄Ge₁₃, which adopts a new structural model in /4₁/amd.Item Properties-Driven Synthesis, Structural Insights, and Discovery of Complex Intermetallics and Alloys(2017-08) Oswald, Iain W. H.; 0000-0002-5466-0405 (Oswald, IWH); Chan, Julia Y.Understanding the intimate relationship between the structure and physical properties of a material is one of the central goals of solid state chemistry. As subtle structural changes can have wide ranging effects on electrical and magnetic properties, it is necessary to fully, and correctly, characterize and elucidate the structure. This dissertation presents the results from four studies aimed at synthesizing, discovering, and structurally characterizing new complex intermetallic phases and alloys. The first study describes an investigation of structural phase transitions in the new series of magnetocaloric alloys (MnNiSi)1-x(FeCoGe)x (x = 0.36, 0.37, 0.38, 0.39, 0.40). These compounds exhibit coupled magneto-structural transitions, where ferromagnetic ordering coincides with a structural phase transition. Our results indicate the high temperature hexagonal phase (space group P63/mmc) transforms to a low temperature orthorhombic phase (space group Pnma) under ambient pressure; however, low pressure studies (< 1 x 10-2 torr) reveal anomalous behavior wherein the high temperature phase persists below the expected phase transition temperature. The second describes a structural study on compounds adopting the Yb3Rh4Sn13-structure type. Single crystal X-ray diffraction experiments revealed the compounds to be highly disordered, with weak, unindexed reflections present. A new structural model was developed for Lu3Ir4Ge13 to account for the disorder. Furthermore, a correlation was found between the electrical resistivity and crystallographic disorder, which was developed into a general rule for predicting electrical properties for this class of material. The third study describes the synthesis and characterization of Er1.33Pt3Ga8. This compound was synthesized using the self-flux method. The structure was initially modeled using space group R3 ̅m with lattice parameters a = 4.3163(2) Å and c = 38.547(17) Å. However, single crystal X-ray diffraction revealed weak, unindexed, supercell reflections. Crystal structure refinements using the modulated structure approach were used to account for these reflections. The synthesis, average structure, and modulated structure are presented. The final study describes the design, synthesis, and characterization of the new series of intergrowth compounds Pr8Fe8.22Sb6Te12, Pr4Mn1.81Sb2Te6, and Ln4Mn2-xSb4+xTe6 (Ln = Ce, Pr, Sm; x = 0.18, 0.36, 0.60, respectively). These compounds are composed of LnTe3 type layers separated by transition metal-antimony containing layers along the c¬-axis. These compounds represent a new class of complex layered materials, and provide insight into strategies aimed at discovering other low dimensional compounds. Additionally, the synthesis and characterization of La(Sb1-xBix)Te (x ~ 0.5) is reported.Item The Role of Ceramic and Glass Science Research in Meeting Societal Challenges: Report from an NSF-Sponsored Workshop(Wiley, 2018-08-20) Faber, Katherine T.; Asefa, Tewodros; Backhaus-Ricoult, Monika; Brow, Richard; Chan, Julia Y.; Dillon, Shen; Fahrenholtz, William G.; Finnis, Michael W.; Garay, Javier E.; Garcia, R. Edwin; Gogotsi, Yury; Haile, Sossina M.; Halloran, John; Hu, Juejun; Huang, Liping; Jacobsen, Steven D.; Lara-Curzio, Edgar; LeBeau, James; Lee, William E.; Levi, Carlos G.; Levin, Igor; Lewis, Jennifer A.; Lipkin, Don M.; Lu, Kathy; Luo, Jian; Maria, Jon-Paul; Martin, Lane W.; Martin, Steve; Messing, Gary; Navrotsky, Alexandra; Padture, Nitin P.; Randall, Clive; Rohrer, Gregory S.; Rosenflanz, Anatoly; Schaedler, Tobias A.; Schlom, Darrell G.; Sehirlioglu, Alp; Stevenson, Adam J.; Tani, Toshihiko; Tikare, Veena; Trolier-McKinstry, Susan; Wang, Hong; Yildiz, Bilge; 0000-0003-4434-2160 (Chan, JY); Chan, Julia Y.Under the sponsorship of the U.S. National Science Foundation, a workshop on emerging research opportunities in ceramic and glass science was held in September 2016. Reported here are proceedings of the workshop. The report details eight challenges identified through workshop discussions: Ceramic processing: Programmable design and assembly; The defect genome: Understanding, characterizing, and predicting defects across time and length scales; Functionalizing defects for unprecedented properties; Ceramic flatlands: Defining structure-property relations in free-standing, supported, and confined two-dimensional ceramics; Ceramics in the extreme: Discovery and design strategies; Ceramics in the extreme: Behavior of multimaterial systems; Understanding and exploiting glasses and melts under extreme conditions; and Rational design of functional glasses guided by predictive modeling. It is anticipated that these challenges, once met, will promote basic understanding and ultimately enable advancements within multiple sectors, including energy, environment, manufacturing, security, and health care.Item Spin Density Wave Instability in a Ferromagnet(Nature Publishing Group) Wu, Yan; Ning, Zhenhua; Cao, Huibo; Cao, Guixin; Benavides, Katherine A.; Karna, S.; McCandless, Gregory T.; Jin, R.; Chan, Julia Y.; Shelton, W. A.; DiTusa, J. F.; McCandless, Gregory T.; Chan, Julia Y.Due to its cooperative nature, magnetic ordering involves a complex interplay between spin, charge, and lattice degrees of freedom, which can lead to strong competition between magnetic states. Binary Fe₃Ga₄ is one such material that exhibits competing orders having a ferromagnetic (FM) ground state, an antiferromagnetic (AFM) behavior at intermediate temperatures, and a conspicuous re-entrance of the FM state at high temperature. Through a combination of neutron diffraction experiments and simulations, we have discovered that the AFM state is an incommensurate spin-density wave (ISDW) ordering generated by nesting in the spin polarized Fermi surface. These two magnetic states, FM and ISDW, are seldom observed in the same material without application of a polarizing magnetic field. To date, this unusual mechanism has never been observed and its elemental origins could have far reaching implications in many other magnetic systems that contain strong competition between these types of magnetic order. Furthermore, the competition between magnetic states results in a susceptibility to external perturbations allowing the magnetic transitions in Fe3Ga4 to be controlled via temperature, magnetic field, disorder, and pressure. Thus, Fe₃Ga₄ has potential for application in novel magnetic memory devices, such as the magnetic components of tunneling magnetoresistance spintronics devices.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.Item The Story Behind Disorder: Determining the Relationship Between Structure and Physical Properties of Disordered Intermetallics(2018-08) Benavides, Katherine Anne; Chan, Julia Y.The synthesis and characterization of single crystalline ternary intermetallics is the primary focus of this dissertation. By focusing on specific structural subunits, we can design materials with tailorable magnetic and electrical properties. Our rationale for the pursuit and design of low dimensional intermetallics is not unlike the assembly of hierarchical structures. We endeavor to grow these materials as bulk high quality single crystals thereby granting us the assurance that intrinsic properties are determined. We grow single crystals primarily by utilizing the flux growth method, which allows the growth of congruently melting and metastable phases. Highlighted in this dissertation are the synthesis, structures, and physical properties of LnMₓGa₃ (Ln = Ho, Er; M = Fe, Co; x < 0.2) of the AuCu₃ type, the La₆MnSb₁₅ structure type, and compounds adopting the La₂Fe₄Sb₅ structure type. Special emphasis is placed on the investigation of the effects of disorder and substitution on emergent physical phenomena. In the case of LnMₓGa₃ (Ln = Ho, Er; M = Fe, Co; x < 0.2), we were motivated to study the insertion of transition metals into compounds adopting the AuCu₃ structure type. Although HoGa₃ has five allotropes, a distorted AuCu₃-type structure is stabilized upon addition of transition metal. The HoMₓGa₃ order antiferromagnetically and the Néel temperatures are influenced by Ho-Ho contact distances. The incorporation of transition metals into the body position of the ErGa₃ host structure resulted in strengthened rare earth coupling as evidenced by higher transition temperatures that what is observed in the parent ErGa₃ compound. We then turned our attention to the La₆MnSb₁₅ structure type, which is comprised of anionic antimony nets and triangular units of rare earth ions. We found that the Mn analogues, La₆MnSb₁₅ (Ln = La, Ce) exhibit long-range occupational disorder that can be modeled using a supercell structure. The Zn-containing compounds Ln₆Mn₁₋ₓZnₓSb₁₅ (x ~ 0.5) and Ln₆ZnSb₁₅ (Ln = La-Pr) were found to be highly disordered but did not exhibit long-range occupational disorder. In our search for highly correlated low-dimensional materials, we posited the idea of “building up” low-dimensional structures by beginning with layered materials and envisioning the incorporation of transition metal sublattices in the final structure. The La₂Fe₄Sb₅ structure type can be thought of as building up of a SmSb2 structure type and a transition metal sublattice with nearly equilateral triangles of iron and the potential for geometric frustration. The rare earth and transition metal sublattices both carry a magnetic moment and exhibit localized magnetism. The synthesis, characterization, and interplay of the f- and d-electrons and the mechanisms of localized and itinerant behavior as a function of Co concentration in La₂Fe₄₋ₓCoₓSb₄․₈Bi₀․₂ (x ~ 0 and 0.5) and Ce₂Fe₄₋ₓCoₓSb₄․₈Bi₀․₂ (x ~ 0.5 and 1) is discussed.