Windows

Get-ChildItem | ForEach-Object {
    $size = (Get-ChildItem $_.FullName -Recurse -ErrorAction SilentlyContinue |
             Measure-Object -Property Length -Sum).Sum
    $sizeMB = [math]::Round($size / 1MB, 2)
    "$($sizeMB) MB`t$($_.Name)"
} | Sort-Object { [double]($_ -split '\s+')[0] } -Descending |
    Out-File "artist_list.txt"