is it allowed in islam to name ones baby girl, amatu salam?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

There is no religious impediment to giving the name "Amah" to a female child if it is added to one of the names of Allah such as "Amat Allah" or "Amat As-Salaam (which means: a female servant of Allah)." This is true as all women are the servants of Allah, The Exalted.

Abu Hurayrah narrated that the Prophet, sallallaahu ʻalayhi wa sallam, said: “None of you should say, ‘My slave (ʻabdi)' or 'my slave girl (amati)' All of you are slaves of Allah and all of your women are slaves of Allah. Rather, you should say, 'My boy (ghulaami)', my slave girl (jaariyyati)', 'my lad (fataayi)' or 'my girl (fataati).’” [Muslim]

Abu Hurayrah said, “The Prophet, sallallaahu ʻalayhi wa sallam, passed by a woman who was sitting and weeping beside a grave and he, sallallaahu ʻalayhi wa sallam, said to her: “Oh servant of Allah; Fear Allah and be patient.” [Musnad Abu Yaʻla, Al-Bukhari, and Muslim]

Allah knows best.