Browsing by Author "Prochaska, L."
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Item Kondo Insulator to Semimetal Transformation Tuned by Spin-Orbit Coupling(American Physical Society, 2017) Dzsaber, S.; Prochaska, L.; Sidorenko, A.; Eguchi, G.; Svagera, R.; Waas, M.; Prokofiev, A.; Si, Q.; Paschen, S.Recent theoretical studies of topologically nontrivial electronic states in Kondo insulators have pointed to the importance of spin-orbit coupling (SOC) for stabilizing these states. However, systematic experimental studies that tune the SOC parameter λ SOC in Kondo insulators remain elusive. The main reason is that variations of (chemical) pressure or doping strongly influence the Kondo coupling J K and the chemical potential μ —both essential parameters determining the ground state of the material—and thus possible λ SOC tuning effects have remained unnoticed. Here, we present the successful growth of the substitution series Ce 3 Bi 4 ( Pt 1 − x Pd x ) 3 ( 0 ≤ x ≤ 1 ) of the archetypal (noncentrosymmetric) Kondo insulator Ce 3 Bi 4 Pt 3 . The Pt-Pd substitution is isostructural, isoelectronic, and isosize, and it therefore is likely to leave J K and μ essentially unchanged. By contrast, the large mass difference between the 5 d element Pt and the 4 d element Pd leads to a large difference in λ SOC , which thus is the dominating tuning parameter in the series. Surprisingly, with increasing x (decreasing λ SOC ), we observe a Kondo insulator to semimetal transition, demonstrating an unprecedented drastic influence of the SOC. The fully substituted end compound Ce 3 Bi 4 Pd 3 shows thermodynamic signatures of a recently predicted Weyl-Kondo semimetal.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 .