focusElevation property

The z-coordinate at which to place this button relative to its parent when the button has the input focus.

This controls the size of the shadow below the floating action button.

Defaults to 8, the appropriate elevation for floating action buttons while they have focus. The value is always non-negative.

See also:

• elevation, the default elevation.
• highlightElevation, the elevation when the button is pressed.
• disabledElevation, the elevation when the button is disabled.