DC and AC Magnetization Study of Complex Ilmenite Oxides (Ni1-xCox)TiO3 (0.05 < x < 0.8)

TL;DR

This study investigates the magnetic properties of complex Ni-Co titanate oxides, revealing unique magnetic transitions, unexpected negative magnetization, and dynamic magnetic behavior across different temperatures and frequencies.

Contribution

It provides new insights into the magnetic phases and behaviors of (Ni1-xCox)TiO3 solid solutions, including the discovery of a novel intermediate magnetic phase.

Findings

Two magnetic transitions at 27 K and 63 K

Observation of negative magnetization at low temperatures

Frequency-dependent AC magnetization behavior

Abstract

Ilmenite solid-solutions, (Ni1-xCox)TiO3 (0.05 < x < 0.8), were synthesized at ambient atmosphere through solid-state reaction and were studied by energy dispersive spectroscopy of X-rays, X-ray diffraction, and DC and AC magnetometry. Temperature dependent DC magnetic measurements revealed two transitions. The first took place at around 27 K and the second at 63 K. The low-temperature phase was antiferromagnetic. The phase observed between 27 and 63 K is characteristic to the solid-solution and is not found in either of the constituent members. A fit of the data to the Curie-Weiss law gave magnetic moment values which were significantly larger than the values based on the quenched orbital momentum assumption. Zero-field-cooled magnetization measurements with weak magnetic field revealed unexpected negative magnetization at low temperatures. Below 63 K the DC magnetization exhibited time dependent behavior. Frequency and magnetic field dependent AC magnetization is also addressed.