In This Moment: The name of an American metalcore band At this moment: An English phrase involving the correct use of a preposition I hope that answers your question!

Su. Ki is correct but I have ne'er heard any American to use "In" this moment before whether in films, news or in reality to contact them. To make this sort of mistake in preposition is very unusual to native English speakers really. In sounds to prolong in limited time or space, not to match moment so short I suppose. Or you may check out English dictionary by yourself.

At we use for a PRECISE TIME, in for MONTHS, YEARS, CENTURIES and LONG PERIODS and on for DAYS and DATES, so it'd be "at this moment" correct. Good luck!