title: Anomalous transport properties of the half-metallic ferromagnets Co₂TiSi, Co₂TiGe and Co₂TiSn.
abstract: In this work, the theoretical and experimental investigations of Co₂TiZ (Z=Si, Ge or Sn) compounds are reported. Half-metallic ferromagnetism is predicted for all three compounds with only two bands crossing the Fermi energy in the majority channel. The magnetic moments fulfil the Slater-Pauling rule and the Curie temperatures are well above room temperature. All compounds show a metallic-like resistivity for low temperatures up to their Curie temperature, above the resistivity changes to semiconducting-like behaviour. A large negative magnetoresistance (MR) of 55 per cent is observed for Co₂TiSn at room temperature in an applied magnetic field of μ(0)H=4T, which is comparable to the large negative MRs of the manganites. The Seebeck coefficients are negative for all three compounds and reach their maximum values at their respective Curie temperatures and stay almost constant up to 950 K. The highest value achieved is -52 μVK(-1) for Co₂TiSn, which is large for a metal. The combination of half-metallicity and the constant large Seebeck coefficient over a wide temperature range makes these compounds interesting materials for thermoelectric applications and further spincaloric investigations.
authors.affiliation: Institut für Anorganische und Analytische Chemie, and Johannes Gutenberg-Universität, 55099 Mainz, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Barth
authors.forename: Gerhard H
authors.initials: GH
authors.lastname: Fecher
authors.forename: Benjamin
authors.initials: B
authors.lastname: Balke
authors.forename: Tanja
authors.initials: T
authors.lastname: Graf
authors.forename: Andrey
authors.initials: A
authors.lastname: Shkabko
authors.forename: Anke
authors.initials: A
authors.lastname: Weidenkaff
authors.forename: Peter
authors.initials: P
authors.lastname: Klaer
authors.forename: Michael
authors.initials: M
authors.lastname: Kallmayer
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Elmers
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Shigenori
authors.initials: S
authors.lastname: Ueda
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Claudia
authors.initials: C
authors.lastname: Felser
mesh_terms: D002244:Carbon / Q000737:chemistry*; D004560:Electricity; D004581:Electronics; D005857:Germanium / Q000737:chemistry*; D006358:Hot Temperature; D007501:Iron / Q000737:chemistry; D008280:Magnetics; D017895:Manganese Compounds / Q000737:chemistry; D012542:Scattering, Radiation; D017640:Silicates / Q000737:chemistry*; D012984:Software; D013696:Temperature; D013816:Thermodynamics; D014001:Tin / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D017895:Manganese Compounds; D017640:Silicates; C494384:manganite; D005857:Germanium; C103828:titanium silicide; D014001:Tin; D002244:Carbon; D014025:Titanium; D007501:Iron