Reference to array of objects in Sanity

Im having issues with references in Sanity. Im setting some color themes in the root of my Sanity schema:

defineField({
      name: 'articletheme',
      title: 'Article theme',
      description: 'Create 4 themes for article blocks',
      type: 'array',
      validation: (Rule) => Rule.required(),
      of: [{ type: 'articleThemeBlock' }],
    }),

In one of the blocks I would like to reference the theme array to select which color theme that block should use.

Ive tried this, but it fails:

defineField({
      name: 'theme',
      title: 'Theme',
      type: 'reference',
      to: [
        {
          type: 'array',
          of: [
            {
              type: 'articletheme',
            },
          ],
        },
      ],
    }),

Any suggestions?