A minor major 7th chord is created by adding a natural 7th degree to any minor chord. For example, a Cm (maj7) chord contains the notes C, Eb, G and B (1, b3, 5 and 7). Here are some common open minor major 7th chord shapes.
Dm(maj7)
Ebm(maj7)
Em(maj7)
Fm(maj7)
F#m(maj7)
Gm(maj7)
Bm(maj7)
Cm(maj7)
Dbm(maj7)
Abm(maj7)
Am(maj7)
Bbm(maj7)