Conventional superconductivity and charge-density-wave ordering in Ba1xNaxTi2Sb2O

We have investigated the low-temperature physical properties of BaTi2Sb2O and Ba1−xNaxTi2Sb2O (x=0.05, 0.1, 0.15, 0.2, 0.25, 0.3) by means of muon spin rotation (�SR) and SQUID magnetometry. Our measurements reveal the absence of magnetic ordering below TDW=58 K in the parent compound. Therefore the phase transition at this temperature observed by magnetometry is most likely due to the formation of a charge-denisty wave (CDW). Upon substitution of barium by sodium in Ba1−xNaxTi2Sb2O we find for x=0.25 superconductivity with a maximum Tc=5.1 K in the magnetization and a bulk Tc,bulk=4.5 K in the �SR measurements. The temperature dependency of the London penetration depth �−2(T) of the optimally doped compound can be well explained within a conventional weak-coupling scenario in the clean limit. DOI: https://doi.org/10.1103/PhysRevB.88.140501 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-86046 Originally published at: von Rohr, Fabian; Schilling, Andreas; Nesper, Reinhard; Baines, Chris; Bendele, Markus (2013). Conventional superconductivity and charge-density-wave ordering in Ba1xNaxTi2Sb2O.PhysicalReviewB, 88(14) : 140501. DOI: https://doi.org/10.1103/PhysRevB.88.140501 Conventional superconductivity and charge-density-wave ordering in Ba1-xNaxTi2Sb2O Fabian von Rohr, 2, ∗ Andreas Schilling, Reinhard Nesper, Chris Baines, and Markus Bendele Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland Lab. of Inorg. Chemistry, ETH Zürich, Wolfgang-Pauli-Str. 10, CH-8093 Zürich, Switzerland Physik-Institut der Universität of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland Dipartimento di Fisica, Universit di Roma ”La Sapienza”, P.le Aldo Moro 2, 00185 Roma, Italy (Dated: October 11, 2013) We have investigated the low temperature physical properties of BaTi2Sb2O and Ba1-xNaxTi2Sb2O (x = 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) by means of muon spin rotation (μSR) and SQUID magnetometry. Our measurements reveal the absence of magnetic ordering below TDW = 58 K in the parent compound. Therefore the phase transition at this temperature observed by magnetometry is most likely due to the formation of a charge density wave (CDW). Upon substitution of barium by sodium in Ba1-xNaxTi2Sb2O we find for x = 0.25 superconductivity with a maximum Tc = 5.1 K in the magnetization and a bulk Tc,bulk = 4.5 K in the μSR measurements. The temperature dependency of the London penetration depth λ−2(T ) of the optimally doped compound can be well explained within a conventional weak-coupling scenario in the clean limit.