Barrier

You create a selectively permeable 5ft wide 8ft tall arcane shield within 5ft front of you. The shield is translucent and shimmers with a magical aura. It acts as full cover from ranged attacks and spells, but only protects from one side allowing for a creature to attack from behind it.

Creatures are able to go through the cover, and it does not protect against area of effect attacks. If the caster moves away from the spell it remains until either the duration expires, or the caster casts another concentration spell. 

The spell can be casted in areas smaller than 5ft as it does not displace objects.