Magnetars form interesting visions about the stars.

The difference between a magnetar and a neutron star is only weight. The lightweight neutron stars are called magnetars. Light neutron stars' structure causes their magnetic field to be stronger than a heavier neutron star. 

The X-ray emission around neutron stars is an interesting phenomenon. X-ray emission around magnetar forms when particles with high energy levels hit the material around them. 

The strength of that emission depends on debris around the neutron star. Young neutron stars form stronger X-ray emissions than old ones. The reason for that is, there is more supernova debris around them than old neutron stars. 

A strong magnetic field accelerates particles to extremely high speeds. And when those particles hit particles around them they cause high-energy radiation. Also when particles fall to the neutron star's the impact energy forms high-energy radiation. 

Magnetars are lightweight neutron stars with magnetic fields that are extremely strong. The magnetar's shell spins faster than a heavy neutron star's shell. The thing that forms a neutron star's magnetic field is the neutron star's shell spinning speed according to its inner structures. 

So neutron stars are acting like extremely fast-spinning generators. The new magnetar has no atmosphere at all. The article below this text says; "the polarization at low energies is telling us that the magnetic field is likely so strong to turn the atmosphere around the star into a solid or a liquid, a phenomenon known as magnetic condensation".  (ScitechDaily.com/“Completely Unexpected” – Scientists Discover a Magnetized Dead Star With a Solid Surface)

The gravitation is also one of the reasons why neutron stars have no atmosphere. The gravitation smashes gas to a solid form on its shell. But the interaction between neutron stars and their environment is much more complicated. Than only gravitational and electromagnetic interaction. There is more about those interactions later in this text. 

But there can be many or at least a couple of reasons for that. The magnetic field of a magnetar is very powerful even in comparison with other neutron stars. And the difference between that magnetic field's north and south poles is much higher than Earth or some other planet. 

When things like water molecules hit to magnetar's shell. A strong magnetic field will rip ion bonds into pieces. Also, centripetal forces on the magnetar's surface are very strong. So ions start to travel to magnetar's poles, and there the high power electron radiation pushes those ions away. This is the reason why neutron stars have no atmosphere. 

The interaction between neutron stars (also magnetars are neutron stars) is more complicated than just the electromagnetic interaction. The gravitational field of neutron stars is massive. And that also causes a situation where the gas turns solid. 

But also electromagnetic interaction is powerful. The spin of magnetars is extremely high. It's almost 430000 rpm. So the centripetal force on the shell of that object is also powerful. Fast spin is one of the reasons why modeling the interactions between neutron stars is so hard to model. 

https://scitechdaily.com/completely-unexpected-scientists-discover-a-magnetized-dead-star-with-a-solid-surface/