Browsing by Author "Svanidze, Eteri"
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Item Doping induced quantum phase transition in the itinerant ferromagnet scandium indium(2012) Svanidze, Eteri; Morosan, EmiliaExamination of quantum critical points of itinerant electron systems will aid with understanding of d-electron magnetism that exhibits both local and itinerant characteristics in different families of compounds. Doping-induced quantum phase transition of the itinerant ferromagnet Sc 3.1 In that is composed of non-magnetic elements is the focus of our work. Polycrystalline samples of (Sc 1-x Lu x ) 3.1 In with 0≤ x≤ 0.08 were prepared by arcmelting and then annealing for an extended period of time. Susceptibility measurements were performed in an applied magnetic field H = 0.1 T for temperatures T = 1.85 K to 300 K. Linearity of Arrott plots in low-field region was significantly improved by implementing the non-mean-field Arrott-Noakes technique where plotting M 1/β vs. ( H/M ) 1/γ is used to determine both the Curie temperature and composition. Modified Arrott plot approach was used in order to determine the new critical exponents β, γ and δ that better describe this compound. The Curie temperature of the Sc 3.1 In compound was found to be T C = 4.4 K and the critical composition x c = 0.02. This work was supported by NSF DMR 0847681.Item High hardness in the biocompatible intermetallic compound β-Ti3Au(AAAS, 2016) Svanidze, Eteri; Besara, Tiglet; Ozaydin, M. Fevsi; Tiwary, Chandra Sekhar; Wang, Jiakui K.; Radhakrishnan, Sruthi; Mani, Sendurai; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Ajayan, Pulickel M.; Morosan, E.The search for new hard materials is often challenging, but strongly motivated by the vast application potential such materials hold. Ti3Au exhibits high hardness values (about four times those of pure Ti and most steel alloys), reduced coefficient of friction and wear rates, and biocompatibility, all of which are optimal traits for orthopedic, dental, and prosthetic applications. In addition, the ability of this compound to adhere to ceramic parts can reduce both the weight and the cost of medical components. The fourfold increase in the hardness of Ti3Au compared to other Ti–Au alloys and compounds can be attributed to the elevated valence electron density, the reduced bond length, and the pseudogap formation. Understanding the origin of hardness in this intermetallic compound provides an avenue toward designing superior biocompatible, hard materials.Item Search, Discovery, Synthesis and Characterization of Itinerant Magnets Composed of Non-magnetic Constituents(2015-04-23) Svanidze, Eteri; Morosan, Emilia; Kono, Junichiro; Du, Rui RuiThe origin of magnetism in metals has been traditionally discussed in two diametrically opposite limits: itinerant and local. Itinerant magnetism, caused by conduction electrons, has been of interest due to intriguing phenomena that frequently accompany it: heavy fermion behavior, coexistence of superconductivity and magnetism, metamagnetic transitions, spin- and cluster-glass behavior, multisublattice magnetism, non-Fermi liquid behavior, and quantum criticality. Surprisingly, while many systems exhibit both local and itinerant magnetism, only two are known to contain no local moment ions: Sc3In and ZrZn2. Doping experiments on Sc3In were used to investigate the effects of both magnetic (Er) and non-magnetic (Lu) substitutions within the itinerant matrix. While the former induces a cluster-glass state, the latter drives the system through a quantum phase transition. A novel Arrott-Noakes scaling indicates that Sc3In cannot be described by the mean-field theory, contrary to what has been seen in ZrZn2. This indicates that ZrZn2 and Sc3In are drastically different, which is likely associated with the dimensionality of spin fluctuations. Given these disparities between two seemingly analogues systems, more itinerant compounds containing non-magnetic elements are needed. While the Stoner criterion for band ferromagnetism calls for high density of states at the Fermi level together with strong electron correlations, more conditions are likely at play. A systematic search among 3d systems resulted in the discovery of the first itinerant antiferromagnet composed of non-magnetic elements TiAu. The spin density wave antiferromagnetic ordering separates this compound from the previously reported ferromagnetic ones. Furthermore, perturbation of TiAu lattice with doping resulted in an antiferromagnetic quantum critical point, which can provide insights on the validity of the self-consistent renormalization theory of spin fluctuations in itinerant magnets.Item Spin Dynamics of (Sc1−xLux)3.1In Studied by Electron Spin Resonance(Springer, 2018) Cable, Archie; Svanidze, Eteri; Santiago, Jessica; Morosan, Emilia; Sichelschmidt, JörgThe electron spin resonance (ESR) of conduction electrons is reported for the weak itinerant ferromagnet Sc3.1In which, upon chemical substitution with Lu, shows a suppression of ferromagnetic correlations. A well-defined ESR lineshape of Dysonian type characterizes the spectra. The ESR linewidth, determined by the spin dynamics, displays a broad minimum only for the Sc3.1In compound. We discuss the results using the mechanism of exchange enhancement of spin-lifetimes.