title: Magnetic glass state and magnetoresistance in SrLaFeCoO6double perovskite.
abstract: Unusual features in magnetization resembling the kinetic arrest of a magnetic glass state are observed in the La-doped double perovskite, SrLaFeCoO6. Neutron powder diffraction experiments confirm the presence of antisite disorder as well as a lack of long-range magnetic order down to 4 K in this double perovskite which displays spin glass-like features in dc and ac susceptibilities. Magnetic relaxation observed through cooling and heating under unequal fields (CHUF) point towards unusual domain dynamics which is supported by a broad memory effect. Among the two anomalies that are observed at [Formula: see text] 75 K and at [Formula: see text] 250 K in the magnetic measurements, the former is associated with a spin-freezing temperature below which the magnetic glass state is experimentally verified. The magnetometric experiments detailed in the paper bring out the non-equilibrium metastable magnetic states in this disordered magnetic system. The magnetic glass state described above manifests in the electrical resistivity [Formula: see text] through the formation of a 'hard gap' because of the spin-exchange energy following the formation of magnetic glass. It is observed that the combination of disorder and magnetic glass state leads to a large, negative magnetoresistance (MR) of  ≈47[Formula: see text] at 5 K in 8 T.
authors.affiliation: Department of Physics, Low Temperature Physics Lab, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: R
authors.initials: R
authors.lastname: Pradheesh
authors.forename: Harikrishnan S
authors.initials: HS
authors.lastname: Nair
authors.forename: G R
authors.initials: GR
authors.lastname: Haripriya
authors.forename: Anatoliy
authors.initials: A
authors.lastname: Senyshyn
authors.forename: Tapan
authors.initials: T
authors.lastname: Chatterji
authors.forename: V
authors.initials: V
authors.lastname: Sankaranarayanan
authors.forename: K
authors.initials: K
authors.lastname: Sethupathi