Superconductivity in monocrystalline YNiSi3 and LuNiSi3

Author(s)

Arantes, Fabiana R. ; Aristizabal-Giraldo, Deisy ; Mayoh, Daniel A. ; Yamane, Yu ; Yang, Chongli ; Lees, Martin R. ; Osorio-Guillen, Jorge M. ; Takabatake, Toshiro ; Avila, Marcos A.

• Document type: Journal article
• Source: PHYSICAL REVIEW B; v. 99, n. 22, p. 14-pg., 2019-06-11.

Abstract

We report the discovery of bulk superconductivity in the ternary intermetallics YNiSi3 and LuNiSi3. High-quality single crystals were grown via the Sn-flux method and studied using magnetization, specific-heat, and resistivity measurements at low temperatures. The critical temperatures obtained from these different techniques are in very good agreement and yield T-c = 1.36(3) K and T-c = 1.61(2) K for YNiSi3 and LuNiSi3, respectively. Magnetization measurements indicate that both compounds are among the rare cases where type-I superconductivity occurs in a ternary intermetallic, however, the jump in the specific heat at the transition is lower than the value expected from BCS theory (Delta C-el/gamma T-n(c) = 1.43) in both materials and is equal to 1.14(9) and 0.71(5) for the Y and Lu compounds, respectively. Resistivity measurements exhibit sharp transitions but with critical fields mu H-0(c)(0) (approximate to 0.05 T for YNiSi3 and approximate to 0.08 T for LuNiSi3) considerably higher than those obtained from the magnetization and specific heat (approximate to 0.01 T). First-principles density functional theory calculated electronic structure shows that these compounds have highly anisotropic and complex Fermi surfaces with one electronic and two holelike branches. One hole branch and the electron branch have a large cylindrical topology connecting the first Brillouin-zone boundaries, the former being built up by the hybridization of Y(Lu) d, Ni d, and Si p states, and the latter being built up by Ni d and Si p states. The calculated phononic structures indicate that the coupling of the Y(Lu), Ni d, and Si p electrons in the low-lying optical phonon branches is responsible for the formation of Cooper pairs and the observed superconducting state. Therefore, these compounds can be classified as anisotropic three-dimensional metals with multiband superconducting ground states in the weak-coupling regime. (AU)

• FAPESP's process: 12/17562-9 - Preparation of oriented single crystals for studies on electronic, magnetic and thermal anisotropies
• Grantee: Marcos de Abreu Avila
• Support Opportunities: Regular Research Grants
• FAPESP's process: 14/20365-6 - Preparation and characterization of new thermoelectric clathrates containing trivalent rare earths and mixed acceptors
• Grantee: Fabiana Rodrigues Arantes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 11/19924-2 - Study and development of advanced novel materials: electronic, magnetic and nanostructured: an interdisciplinary approach
• Grantee: Carlos Rettori
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 17/01827-7 - Thermoelectric characterization of singlecrystalline type-I clathrates Ba8GayMzGe46-y-z (M = Au, Ag, Cu) and Ba8-xRxGayAgzGe46-y-z (R = La, Ce, Eu)
• Grantee: Fabiana Rodrigues Arantes
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor