Asking my PhD mentor to be my referee for PhD position

Question

I'm a Master student in Belgium, 2nd year, doing my Master thesis. I have a supervisor/promoter (university professor) and a PhD student as a daily mentor, we work together and get along great.

I started looking up PhD positions in and out of the country, and most positions ask for 3 referees informations. I'm an international student in Belgium, so I only knew my professors since last year, and I don't know how to ask them, I asked my current thesis supervisor and he accepted, but the other professors I was never close to them, so would it be ok to ask the daily mentor to be a referee instead? She's a PhD student in her 4th year with more than enough experience in the field.

If not, how do I even open the topic with the other professors? I don't know if they remember me. I was never an outstanding student, but I got by just fine.

Answer 1

Yes, you can ask her for a letter, though one from a professor would be much (much) better. The tradeoff is that while she knows you well and can speak to your skills, she has not yet proven herself in academia, so some (not all) will discount such letter.

But, I suggest that you ask her for advice about who would be a good letter writer. You and she might together approach one of the professors who knows you a bit better than others.

And, some places put much more emphasis on such letters than others. They are quite important in the US, but less so in some other countries. Other parts of your record may be more important.