Magnetic switching in Cr x (x = 2–8) and its oxide cluster series

Highlights: • First report on the ionization and oxidation effect on Cr_x (x = 2–8) clusters under DFT. • Magnetism especially noncollinearity in Cr_x, Cr_x⁻ and Cr_xO₂ series is reported. • Cr_x and Cr_x⁻ are found to prefer noncollinear spin correlations. • Oxidation stabilizes Cr_x and Cr_x⁻ clusters into collinear spin alignments. • Magnetic switching in even-odd Cr atom Cr_x and Cr_xO₂ clusters is observed. • An even-odd Cr atom dependent reactivity in Cr_x and Cr_xO₂ clusters is also noticed. First principle studies on the magnetic ground state structure, noncollinearity, binding energy and various electronic properties of a series of Cr_x (x = 2–8) clusters are performed. In order to investigate the effect of ionization and oxidation on the clusters, the anionic (Cr_x⁻) and oxidized (Cr_xO₂) analogues of those clusters are also studied in detail. To calculate adiabatic electron affinity of Cr_xO₂ clusters, additionally Cr_xO₂⁻ analogues are also included in the present work. An interesting even (non-magnetic) – odd (magnetic) feature in the considered cluster series has been noticed. The similar behavior is also reflected from their electronic properties as even (less reactive) – odd (more reactive). The most of the neutral and ionized chromium clusters, viz., Cr_x and Cr_x⁻ are found to be noncollinear in their ground states, whereas oxidation stabilized those clusters into the collinear spin alignments. The bond distances of Cr clusters are found to be close with available experimental studies.