A promising platform for ferrimagnetic spintronics: transition-metal oxide NiCo 2 O 4 with robust perpendicular magnetic anisotropy

Abstract Ferrimagnetic (FIM) spintronics presents a promising avenue for integrating the advantages of both ferromagnetic (FM) and antiferromagnetic (AFM) spintronics, such as FM-like field operation of magnetization and AFM-like fast dynamics. Moreover, the use of perpendicular-magnetic-anisotropy (PMA) materials is essential for achieving low power consumption in the electrical manipulation of magnetization. This study reports the magnetic and transport properties of a highly promising transition-metal oxide (TMO), NiCo 2 O 4 (NCO), which exhibits ferrimagnetic order and robust PMA at room temperature. The NCO thin films were epitaxially grown using pulsed laser deposition (PLD). The samples grown at low temperatures exhibit a metallic behavior with a Curie temperature ( T C ) of about 400 K. The anomalous Hall effect (AHE) measurements demonstrate a robust PMA independent of the NCO film thickness, which overcomes a long-standing challenge in FM spintronics. The AHE sign can be tuned flexibly via growth conditions, thereby providing an optimal platform for the FIM spin transport study. The carrier scattering mechanism and the magnetization switching process are independent from each other in thick films but correlated in thin films due to finite size effects. NCO films grown at high temperatures exhibit semiconducting behavior, whereby the electrical properties are determined by the thermal activation of both carrier hopping and spin fluctuations. In conclusion, NCO films provide ideal platforms for the investigation and development of FIM spintronics.