That's amazing! Even a few shipment of neodymium magnets could be sent. Then in a 1,000 years after the collapse of our civilization and emergence of a new technological civilization there'd be a Mars with much thicker atmosphere and potentially even liquid water.

Even for regular human asteroid mining it looks like an artificial magnetosphere would be possible: https://physicsworld.com/a/magnetic-shield-could-protect-spa...

It's still surprising to me that the notion isn't prevalent in sci-fi or even hard sci-fi. Though as you mention even a modified MRI could do the job.