In doubt, if you use a quantifier, always put the adjective after the noun :

Une étude plus récente

Un professeur aussi mauvais

Orally it’s what sounds most natural, and will always be accepted. Sometimes you can put in in front of the noun if you want, but it sounds more formal.

So it’s always correct after, and sometimes also correct before. I recommend you use it after unless you know exactly what you’re doing.