stop, suppress
遏 centers on forcibly halting or holding back movement or expression: stopping something in its tracks or suppressing it.
遏 combines 辶 (movement) with 曷, which likely contributes the sound and may relate to stopping or blocking. The exact historical development is uncertain.
The movement radical 辶 wraps around 曷 like a barrier on a path. Picture a roadblock that stops all traffic: 遏 means to stop or suppress.
For アツ, imagine a heavy gate that stops movement with a loud 'ats!' sound as it slams shut: ats -> アツ, and the path is blocked.