Browsing by Author "Svanidze, E."
Now showing 1 - 7 of 7
Results Per Page
Sort Options
Item An itinerant antiferromagnetic metal without magnetic constituents(Nature Publishing Group, 2015) Svanidze, E.; Wang, Jiakui K.; Besara, T.; Liu, L.; Huang, Q.; Siegrist, T.; Frandsen, B.; Lynn, J.W.; Nevidomskyy, Andriy H.; Gamża, Monika B.; Aronson, M.C.; Uemura, Y.J.; Morosan, E.The origin of magnetism in metals has been traditionally discussed in two diametrically opposite limits: itinerant and local moments. Surprisingly, there are very few known examples of materials that are close to the itinerant limit, and their properties are not universally understood. In the case of the two such examples discovered several decades ago, the itinerant ferromagnets ZrZn2 and Sc3In, the understanding of their magnetic ground states draws on the existence of 3d electrons subject to strong spin fluctuations. Similarly, in Cr, an elemental itinerant antiferromagnet with a spin density wave ground state, its 3d electron character has been deemed crucial to it being magnetic. Here, we report evidence for an itinerant antiferromagnetic metal with no magnetic constituents: TiAu. Antiferromagnetic order occurs below a Néel temperature of 36 K, about an order of magnitude smaller than in Cr, rendering the spin fluctuations in TiAu more important at low temperatures. This itinerant antiferromagnet challenges the currently limited understanding of weak itinerant antiferromagnetism, while providing insights into the effects of spin fluctuations in itinerant–electron systems.Item Band Jahn-Teller structural phase transition inᅠY2In(American Physical Society, 2018) Svanidze, E.; Georgen, C.; Hallas, A.M.; Huang, Q.; Santiago, J.M.; Lynn, J.W.; Morosan, E.The number of paramagnetic materials that undergo a structural phase transition is rather small, which can perhaps explain the limited understanding of the band Jahn-Teller mechanism responsible for this effect. Here we present a structural phase transition observed in paramagnetic Y2In at temperature T0=250±5 K. Below T0, the high-temperature hexagonal P63/mmc phase transforms into the low-temperature orthorhombic Pnma phase. This transition is accompanied by an unambiguous thermal hysteresis of about 10 K, observed in both magnetic susceptibility M/H(T) and resistivity ρ(T), indicating a first-order transition. Band structure calculations suggest a band Jahn-Teller mechanism, during which the degeneracy of electron bands close to the Fermi energy is broken. We establish that this structural phase transition does not have a magnetic component; however, the possibility of a charge density wave formation has not been eliminated.Item Cluster-glass behavior induced by local moment doping in the itinerant ferromagnet Sc3.1In(American Physical Society, 2013) Svanidze, E.; Morosan, E.In the presented work, Sc3.1In, a weak itinerant ferromagnet with no magnetic constituents, is doped with Er3+ local moment ions, to form (Sc1−xErx )3.1In. As x increases, theWeiss-like temperature θ stays positive and nearly triples up to x = 0.10. Moreover, Er doping of as little as x = 0.02 induces a cluster-glass state, which persists up to x = 0.10, as evidenced by dc and ac susceptibility measurements, and confirmed by the Vogel-Fulcher Analysis.Item Non-Fermi Liquid Behavior Close to a Quantum Critical Point in a Ferromagnetic State without Local Moments(American Physical Society, 2015) Svanidze, E.; Liu, L.; Frandsen, B.; White, B.D.; Besara, T.; Goko, T.; Medina, T.; Munsie, T.J.S.; Luke, G.M.; Zheng, D.; Jin, C.Q.; Siegrist, T.; Maple, M.B.; Uemura, Y.J.; Morosan, E.A quantum critical point (QCP) occurs upon chemical doping of the weak itinerant ferromagnet Sc3.1In. Remarkable for a system with no local moments, the QCP is accompanied by non-Fermi liquid behavior, manifested in the logarithmic divergence of the specific heat both in the ferro-and the paramagnetic states, as well as linear temperature dependence of the low-temperature resistivity. With doping, critical scaling is observed close to the QCP, as the critical exponents δ, γ, and β have weak composition dependence, with δ nearly twice and β almost half of their respective mean-field values. The unusually large paramagnetic moment μPM∼1.3μB/F.U. is nearly composition independent. Evidence for strong spin fluctuations, accompanying the QCP at xc=0.035±0.005, may be ascribed to the reduced dimensionality of Sc3.1In, associated with the nearly one-dimensional Sc-In chains.Item Pressure effects in the itinerant antiferromagnetic metal TiAu(American Physical Society, 2017) Wolowiec, C.T.; Fang, Y.; McElroy, C.A.; Jeffries, J.R.; Stillwell, R.L.; Svanidze, E.; Santiago, J.M.; Morosan, E.; Weir, S.T.; Vohra, Y.K.; Maple, M.B.We report the pressure dependence of the Néel temperature T N up to P ≈ 27 GPa for the recently discovered itinerant antiferromagnet (IAFM) TiAu. The T N ( P ) phase boundary exhibits unconventional behavior in which the Néel temperature is enhanced from T N ≈ 33 K at ambient pressure to a maximum of T N ≈ 35 K occurring at P ≈ 5.5 GPa. Upon a further increase in pressure, T N is monotonically suppressed to ∼ 22 K at P ≈ 27 GPa. We also find a crossover in the temperature dependence of the electrical resistivity ρ in the antiferromagnetic (AFM) phase that is coincident with the peak in T N ( P ) , such that the temperature dependence of ρ = ρ 0 + A n T n changes from n ≈ 3 during the enhancement of T N to n ≈ 2 during the suppression of T N . Based on an extrapolation of the T N ( P ) data to a possible pressure-induced quantum critical point, we estimate the critical pressure to be P c ≈ 45 GPa.Item Quantum critical point in the Sc-doped itinerant antiferromagnet TiAu(American Physical Society, 2017) Svanidze, E.; Besara, T.; Wang, J.K.; Geiger, D.; Prochaska, L.; Santiago, J.M.; Lynn, J.W.; Paschen, S.; Siegrist, T.; Morosan, E.We present an experimental realization of a quantum critical point in an itinerant antiferromagnet composed of nonmagnetic constituents, TiAu. By partially substituting Ti with Sc in Ti 1 − x Sc x Au , a doping amount of x c = 0.13 ± 0.01 induces a quantum critical point with minimal disorder effects. The accompanying non-Fermi liquid behavior is observed in both the resistivity ρ ∝ T and specific heat C p / T ∝ − ln T , characteristic of a two-dimensional antiferromagnet. The quantum critical point is accompanied by an enhancement of the spin fluctuations, as indicated by the diverging Sommerfeld coefficient γ at x = x c .Item Type-I superconductivity in ScGa3 and LuGa3 single crystals(American Physical Society, 2012) Svanidze, E.; Morosan, E.We present evidence of type-I superconductivity in single crystals of ScGa3 and LuGa3, from magnetization, specific heat, and resistivity measurements: low critical temperatures Tc = 2.1–2.2 K; field-induced secondto first-order phase transition in the specific heat, critical fields less than 240 Oe; and low Ginzburg-Landau coefficients κ ≈0.23 and 0.30 for ScGa3 and LuGa3, respectively, are all traits of a type-I superconducting ground state. These observations render ScGa3 and LuGa3 two of only several type-I superconducting compounds, with most other superconductors being type II (compounds and alloys) or type I (elemental metals and metaloids).