Carmichael, 23, arrives on loan from Edinburgh and is a former England Under-20s international. Born and raised in Hong Kong, he joined Leicester Tigers' academy in 2019 when his family moved back to the UK.
Playing a pair of PREM Rugby Cup games for the Tigers before joining Edinburgh in 2024, the 6-foot-11 forward (pictured above) has played three times for Scotland's capital club.
Head coach Dan McFarland said: "Rob is a talented prospect who will provide valuable depth for us during a period of the season where we are playing across multiple competitions."
He is joined by Barreto (pictured above), the scrum-half who has represented Scotland at Under-20s and 7s levels.
Born in Portugal but moving to the UK early into his childhood, Kaleem was on the books of Glasgow Warriors early in his career before focusing primarily on the 7s game.
Welcoming him to Newcastle, McFarland said: "Kaleem is a skilful player who has a good opportunity over the next few weeks, and we look forward to seeing how he goes in our environment."
ROB CARMICHAEL BIOG
Position: Lock
Born: 4/4/2003
Height: 2.10m (6 foot 11)
Weight: 125kg (19 stone 9)
Honours: England U20
KALEEM BARRETO BIOG
Position: Scrum-half
Born: 19/12/1998
Height: 1.73m (5 foot 8)
Weight: 81kg (12 stone 11)
Honours: Great Britain 7s