Evidence of cluster glass phase, exchange bias, reversible magnetocaloric effect and study of electrical properties in Ni1−xCdxCr2O4 (x = 0–0.30) spinel.

Effect of cadmium (Cd) substitution on magnetic and electrical properties of spinel Ni1−xCdxCr2O4 (x = 0–0.30) samples have been studied. Due to non-Jahn–Teller Cd ion substitution, a structural transition from the tetragonal ( I 4 1 / a m d ) to cubic ( F d 3 ¯ m ) phase is seen at room temperature. The long-range competitive ferrimagnetic and antiferromagnetic interactions in the x = 0.05 and 0.10 samples are responsible for the observed large value of coercive and exchange bias field. Cd substitution significantly enhances the antiferromagnetic component of canted spin structure of NiCr2O4 and leads to a cluster glass phase for x = 0.30 samples. Observed memory effect and relaxation of isothermal remanent magnetization confirms the metastability and nonequilibrium dynamics in the glassy phase. For x = 0.20 sample, we have observed reversible magnetocaloric behavior with a maximum negative entropy change of - Δ S M = - 1.031 3 × 10 - 4 cal / g K . Dielectric, impedance and ac conductivity data have been investigated in the temperature range of T = 27–300 K and frequency range of f = 20–105 Hz. Study of impedance spectra and ac conductivity indicates non Debye type of dielectric relaxation and correlated barrier hopping (CBH) of charge carriers is controlling the conduction mechanism in these samples. [ABSTRACT FROM AUTHOR]