The Brentford full-back played in the League One leaders’ 3-1 win against Bristol City as recently as Tuesday night. However the former Manchester City youth team player has fallen out of favour at the London club since Mark Warburton took over as manager when Uwe Rosler moved to Wigan.
Logan’s current contract ends in the summer and he has the chance to relaunch his career at Pittodrie, starting with their biggest game in years.
Aberdeen manager Derek McInnes moved quickly to secure the move when it was made clear that Reading would not renew Michael Hector’s loan deal. That, along with the fact that regular right-back Joe Shaughnessy is suspended this weekend and Ryan Jack is out for two months with a hip injury, proved the catalyst.
Alan Tate, on loan from Swansea City, played in that position recently against Caley Thistle but failed to impress, which means the 26-year-old can expect to start at Tynecastle.
A delighted McInnes said: “We’ve signed Shaleum on a deal to the end of the season and he’ll go into the squad for Saturday. He is a right full-back, he has good pace and energy. He also likes to get forward but is a very good one-on-one defender.
“He’s got good experience, he’s played a lot of games for Brentford but has been in and out of the team lately.
“I just felt, in light of Michael Hector staying at Reading, Joe Shaughnessy being suspended as well as Ryan Jack’s injury it was an area of the team we could do with strengthening.
“So, when the opportunity came up to say he was available, we moved quickly on it and we’re delighted to get him.
“He played on Tuesday so he’s match fit and has the experience to handle the challenges ahead of us.”
It was a busy day of comings and goings at Pittodrie as veteran midfielder Chris Clark was released, while Josh Magennis joined St Mirren on loan.
Of course winger Gregg Wylde also joined the Paisley club earlier in the month but the arrival of Tate, Logan and striker Adam Rooney means there is still plenty of depth to the Aberdeen squad.
There is certainly a high level of expectation that they have the players capable of ending a 14 year wait for an appearance in a major final.
The second best paid squad in the top league will also have the backing of 12,000 supporters at Tynecastle tomorrow.
It’s against that background that St Johnstone have tried to increase the pressure on Aberdeen by deliberately talking up their opponents ahead of the confrontation.
That’s not a psychological ploy that’s liable to affect McInnes given his time in charge of the Perth club as he insists that his former employers are only stating the obvious.
He added: “Of course it’s right to say that Aberdeen are the bigger club with a better history. But, regardless of whether the history has been one of disappointment in cups or winning trophies, it’s neither here nor there.
“For us, as a staff and group of players, it’s the first semi-final we have together and we want to make the most of the opportunity. But St Johnstone have finished above Aberdeen for the last few years, they’ve been in Europe for the last two seasons.
“Just because you are a bigger club, just because you have a bigger support and have a better history that doesn’t make you favourites.
“If we are favourites in some people’s eyes I’d suggest it’s because we’ve done well this season and nothing else.
“However, when we run out on Saturday and three quarters of the ground is Aberdeen fans it’s important we try to utilise that as much as we can.
“I have a confidence and belief in the team that we’ll go there and put in a performance we’re capable of. If we can do that then I feel we’ll give ourselves every opportunity to progress but St Johnstone are always tough opponents.
“We are ahead of them in the league but it’s not by that much and when we’ve played them this season it has been two tight games. They have the same opportunity as we do but, hopefully, we’ll get the job done. “