Universal spin-glass behaviour in bulk LaNiO2, PrNiO2 and NdNiO2

Motivated by the recent discovery of superconductivity in infinite-layer nickelate thin films, we report on a synthesis and magnetization study on bulk samples of the parent compounds RNiO2 (R=La, Pr, Nd). The frequency-dependent peaks of the AC magnetic susceptibility, along with remarkable memory effects, characterize spin-glass states. Furthermore, various phenomenological parameters via different spin glass models show strong similarity within these three compounds as well as with other rare-earth metal nickelates. The universal spin-glass behaviour distinguishes the nickelates from the parent compound CaCuO2 of cuprate superconductors, which has the same crystal structure and d9 electronic configuration but undergoes a long-range antiferromagnetic order. Our investigations may indicate a distinctly different nature of magnetism and superconductivity in the bulk nickelates than in the cuprates.

Superparamagnetic and photocatalytic activity of CoCe0.02Dy0.02Fe1.96O4 nanoparticles synthesized by citrate-gel autocombustion technique

Mitigating organic pollutants by employing semiconducting materials is considered to be green and sustainable route to tackle the environmental problems. Herein, citrate-gel autocombustion method was adopted to synthesize Ce and Dy doped CoFe2O4 and characterized by various analytical techniques. The efficacy of prepared CoCexDyxFe2-2xO4 (x=0-0.04) samples were tested for degradation of Methylene blue (MB) under visible light irradiation. The photocatalytic efficiency of CoCe0.02Dy0.02Fe1.96O4 for degradation of MB was found to be larger than pure CoFe2O4, Degussa P25 and other modified CoFe2O4. The enhanced photocatalytic activity was attributed to improved charge separation and visible light utilization by Ce and Dy into CoFe2O4 system. The super-spin glass behaviour of CoCexDyxFe2-2xO4 confirmed from flat nature of magnetization of FC curve below TB.

Synthesis and characterisation of a quaternary nitride series with spin-glass behaviour: SnxGe1−xFe3N

The new quaternary nitrides SnxGe1−xFe3N are canonical spin glasses that open up the possibility to tune the glassy transition temperature.