Reentrant spin-glass behavior and bipolar exchange-bias effect in “Sn” substituted cobalt-orthotitanate

• Published in: Journal of applied physics 2016-01, Vol.119 (4)
• Main Authors: Nayak, S., Joshi, D. C., Krautz, M., Waske, A., Eckert, J., Thota, S.
• Format: Article
• Language: English
• Subjects: ANTIFERROMAGNETISM; Applied physics; BALANCES; Bias; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COBALT; COBALT IONS; Coercivity; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COOLING; Cooling effects; CORRELATIONS; Dependence; DOPED MATERIALS; Exchanging; Ferrimagnetism; FREQUENCY DEPENDENCE; HYSTERESIS; Hysteresis loops; Lattices (mathematics); LENGTH; MAGNETIC MOMENTS; Magnetic permeability; MAGNETIC SUSCEPTIBILITY; Magnetism; MAGNETIZATION; ORIGIN; Remanence; SLOWING-DOWN; SPIN; SPIN GLASS STATE; Spin glasses; Subgroups; Substitutes; TIN
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4940675

We report the co-existence of longitudinal ferrimagnetic behavior with Néel temperature TN ∼ 46.1 K and reentrant transverse spin-glass state at 44.05 K in Tin (Sn) doped cobalt-orthotitanate (Co2TiO4). The ferrimagnetic ordering is resulting from different magnetic moments of Co2+ on the A-sites (3.87 μ B) and B-sites (5.069 μ B). The magnetic compensation temperature (TCOMP) shifts from 31.74 K to 27.1 K when 40 at. % of “Sn4+” substitutes “Ti4+” at B-sites where the bulk-magnetization of two-sublattices balance each other. For T > TN, the dc-magnetic susceptibility (χ dc = M/Hdc) fits well with the Néel's expression for the two-sublattice model with antiferromagnetic molecular field constants NBB ∼ 15.44, NAB ∼ 32.01, and NAA ∼ 20.88. The frequency dependence of ac-magnetic susceptibility χac data follows the Vogel-Fulcher law, and the power-law of critical slowing-down with “zν” = 6.01 suggests the existence of spin-clusters (where “z” and “ν” being dynamic critical-exponent and correlation length of critical-exponent, respectively). This system exhibits unusual hysteresis loops with large bipolar exchange-bias effect (HEB ∼ 13.6 kOe at 7 K) after zero-field cooling process from an un-magnetized state, and a dramatic collapse of remanence (MR) and coercive field (HC) across TCOMP. The possible origins of such anomalous characteristics were discussed.