title: The exchange bias effect in phase separated Nd(1-x)Sr(x)CoO(3) at the spontaneous ferromagnetic/ferrimagnetic interface.
abstract: We report new results for the exchange bias effect in Nd(1-x)Sr(x)CoO(3) for x = 0.20 and 0.40, where the exchange bias phenomenon is involved with the ferrimagnetic (FI) state in a spontaneously phase separated system. The zero-field-cooled magnetization exhibits FI (T(FI)) and ferromagnetic (FM; T(C)) transitions at ∼23 and ∼70 K, respectively, for x = 0.20. Negative horizontal and positive vertical shifts of the magnetic hysteresis loops are observed when the system is cooled through T(FI) in a positive static magnetic field. A training effect is observed for x = 0.20, which could be interpreted satisfactorily by the spin configurational relaxation model. The unidirectional shifts of the hysteresis loops as a function of temperature exhibit an absence of exchange bias above T(FI) for x = 0.20. Analysis of the cooling field dependence of the exchange bias field and magnetization indicates that the FM clusters consist of a single magnetic domain with an average size of around ∼20 and ∼40 Å for x = 0.20 and 0.40, respectively. The sizes of the FM clusters are close to the percolation threshold for x = 0.20; these grow and coalesce to form the bigger size for x = 0.40 resulting in a weak exchange bias effect.
authors.affiliation: Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India. Center for Advanced Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
authors.forename: M
authors.initials: M
authors.lastname: Patra
authors.forename: M
authors.initials: M
authors.lastname: Thakur
authors.forename: S
authors.initials: S
authors.lastname: Majumdar
authors.forename: S
authors.initials: S
authors.lastname: Giri