助詞N4
〜たばかり
have just done... (very recently)
Structure
V-た形 + ばかり（だ）
Explanation
Verb ta-form + ばかり indicates that an action ended very recently, "just did...", with the speaker feeling the time was short. E.g., 食べたばかりです.
Examples
昼ご飯を食べたばかりです。
I've just had lunch.
日本に来たばかりで、まだ日本語が上手ではありません。
I just arrived in Japan, so my Japanese isn't good yet.
Note
〜たばかりだ is close to 〜たところだ, but ばかりだ subjectively stresses how short the time was. Its meaning is completely different from 〜てばかり.