Browsing by Author "Marcinkova, A."

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    Magnetic and transport properties of the layered transition-metal pnictides R3T4As4O2−δ (R = La, Ce, Pr, Nd, and Sm, T = Ni, Cu)
    (American Physical Society, 2014) Wang, Jiakui K.; Marcinkova, A.; Chen, Chih-Wei; He, Hua; Aronson, Meigan; Morosan, E.
    The magnetic and transport properties of the novel R3T 4As4O2−δ (R = La, Ce, Pr, Nd and Sm, T = Ni and Cu) layered materials were studied using structural and physical properties measurements. Varying the rare-earth ion led to the observation of diverse physical properties including superconductivity for R = La and T = Ni, ferromagnetic or antiferromagnetic order for R = Ce, Pr, and Sm, or spin-glass behavior in Nd3Ni4As4O2−δ. These complex magnetic and electronic properties are discussed in light of the crystalline anisotropy in these layered compounds.
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    Topological metal behavior in GeBi2Te4 single crystals
    (American Physical Society, 2013) Marcinkova, A.; Wang, J.K.; Slavonic, C.; Nevidomskyy, Andriy H.; Kelly, K.F.; Filinchuk, Y.; Morosan, E.
    The metallic character of the GeBi2Te4 single crystals is probed using a combination of structural and physical properties measurements, together with density functional theory (DFT) calculations. The structural study shows distorted Ge coordination polyhedra, mainly of the Ge octahedra. This has a major impact on the band structure, resulting in bulk metallic behavior of GeBi2Te4, as indicated by DFT calculations. Such calculations place GeBi2Te4 in a class of a few known nontrivial topological metals, and explains why an observed Dirac point lies below the Fermi energy at about −0.12 eV. A topological picture of GeBi2Te4 is confirmed by the observation of surface state modulations by scanning tunneling microscopy.
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    Very large magnetoresistance in Fe0.28TaS2 single crystals
    (American Physical Society, 2015) Hardy, Will J.; Chen, Chih-Wei; Marcinkova, A.; Ji, Heng; Sinova, Jairo; Natelson, D.; Morosan, E.
    Magnetic moments intercalated into layered transition metal dichalcogenides are an excellent system for investigating the rich physics associated with magnetic ordering in a strongly anisotropic, strong spin-orbit coupling environment. We examine electronic transport and magnetization in Fe0.28TaS2, a highly anisotropic ferromagnet with a Curie temperature TC∼68.8 K. We find anomalous Hall data confirming a dominance of spin-orbit coupling in the magnetotransport properties of this material, and a remarkably large field-perpendicular-to-plane magnetoresistance (MR) exceeding 60% at 2 K, much larger than the typical MR for bulk metals, and comparable to state-of-the-art giant MR in thin film heterostructures, and smaller only than colossal MR in Mn perovskites or high mobility semiconductors. Even within the FexTaS2 series, for the current x=0.28 single crystals the MR is nearly 100× higher than that found previously in the commensurate compound Fe0.25TaS2. After considering alternatives, we argue that the large MR arises from spin-disorder scattering in the strong spin-orbit coupling environment, and suggest that this can be a design principle for materials with large MR.