Browsing by Author "Benavides, Katherine A."
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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 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 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.