The third mode of Harmonic Minor is known as Ionian #5 or Augmented Major. It is bright and somewhat “dreamy” due to the augmented fifth.

Scale formula

The formula for the Ionian #5 mode is:

 1 - 2 - 3 - 4 - #5 - 6 - 7

As the name suggests, you can think of this the Ionian mode with a raised (sharpened) 5th (#5).

Chords

• maj7#5

Usage

The Ionian #5 mode is the third mode of the Harmonic Minor Scale and is sometimes referred to as the Augmented Major Scale. It is a variation of the Ionian (Major) Scale, but with an augmented (sharp) 5th, giving it a more dreamy, mysterious, and tense sound. This mode is often used in jazz, fusion, progressive rock, and film scoring due to its unique balance of brightness and tension.

Ionian #5 is commonly used in jazz over maj7#5 chords. Play C Ionian #5 over Cmaj7#5 for a floating, surreal melody.

Ionian #5 works great in modal fusion or progressive jazz settings. Instead of resolving strongly, this mode allows for floating, unresolved tension.

In prog rock, Ionian #5 is used for odd time signature passages and sci-fi-like melodies. For example, Dream Theater uses augmented arpeggios that align with Ionian #5.

Ionian #5 is often used in sci-fi, fantasy, and surreal music. Hans Zimmer or John Williams might use Ionian #5 for magical, ethereal cues.