After you have raised your head, and before standing up for the second rak'ah (unit of prayer), you should sit for a brief moment. This is due to the following narration regarding the way that Mālik ibn Ḥuwayrith al-Laythī (may Allah be pleased with him) prayed, as he was describing the prayer of the Prophet (may the peace and blessings of Allah be upon him) prayed:
"...he sat down after getting up from [the second] prostration in the first rak'ah." [al-Bukhārī: 677]