https://wccftech.com/western-digital-plans-for-more-energy-assisted-tech-for-24-tb-and-beyond/

Western Digital has been promoting its Microwave-Assisted Magnetic Recording or MAMR technology for over a couple of years now and aims to move over to more energy-assisted technologies in next-gen, higher-capacities data-center drives.

The reason why the MAMR technology isn't being featured in these drives is because of Western Digital's decision to use the right technology at the right time. Western Digital's plans to use both MAMR and HAMR or Heat Assisted Magnetic Recording in future drives when the technology will allow for it. These drives do plan to use EAMR or Energy Assisted Magnetic Recording, which will allow for higher capacities and areal density when compared to drives without EAMR.