All the following assumes a diatonic gamut of scale degrees.
viio is a diminished triad rooted on the seventh scale degree.
vii is a minor triad rooted on the seventh scale degree.
Which scale has a
vii depends on what degree of the diatonic gamut - letters
ABCDEFG - is the tonic.
Phrygian mode - tonic of
E, key signature of zero sharps/flats - would be a case where
Your chord progression is not in
A minor, not in the proper sense of major/minor keys.
how can I intuitively write this chord with roman numerals?
Roman numerals are normally used to analyze major/minor keys along with certain chromatic alterations, it's for functional harmony analysis.
If you really want to indicate the chords "in
A minor" regardless, then give the key, then you use upper/lower case for major/minor chord quality,
o and usually
+ for diminished/augmented quality, and
♭ to show roots altered from the diatonic key signature. So...
Am, Fm, Dm, Gm, Gmaj jazz/pop chord symbols
Am: i vi iv vii VII, Roman numeral analysis
The jazz/pop chord symbols will probably be easier for someone to read if you want them to be used for performance.
The Roman numeral analysis (RNA) would be to analyze functional harmony where primarily you would be looking at root progression - like noticing your progression is all roots by descending thirds - and finding dominant/tonic relationships, which are not in your progression. Other that those two observations, I think it would be a bit cumbersome to perform from those Roman numerals mostly because your progression isn't using typical functional progressions, I can't rely on commonly known patterns, and I have to think too much to translate those Roman numerals into the actual chords to play.
vii which is a minor triad versus
viio which is a diminished triad can be tricky. Only the little
o makes the difference, and in major/minor keys the Roman numeral seven is generally understood by context to mean a leading tone diminished triad in major or minor, or the subtonic major triad in minor. It can get confusing!
Sometimes in my own notation I use
vii(min) to make clear the chord is a minor triad.
vii, a chord that will be found, but not in usual major/minor tonality.