phd - Is it acceptable to ask a professor who is not your supervisor to give you M.S. thesis topic?

I'm currently a M.S. student. My supervisor give me freedom to choose thesis topic. Since it is so hard for me, I decide to ask another professors whom I consider to be their PhD candidates in future. I have written an email to ask them. Is it a good idea to do so? And is my email appropriate for this purpose?

Dear Professor xxx,

I am a M.S. student at University of xxx-the most prestigious university in xxx- with a major in information technology- multimedia systems. I will graduate on September 2016.

I had the chance to read your publications and some of your articles. I really enjoyed them, and it gave me many ideas for my future research. Due to my strong interest in your research area and considering the experience I have gained from my relevant courses, I believe I can be a beneficial part of your research group, if I get a chance. Since I haven't chosen the topic of my M.S. Thesis, I prefer to ask you to give me some information about the topics you are currently working on, in order to get a higher chance to be your PhD student in future. I know you’re very busy so I appreciate any time you can give me.

Thanks very much,
Sincerely,
xxx

Answer

I do not think it is a good idea to ask this other professor to give you your thesis topic, either asking by email or in person. If you want to be this professor's PhD student in the future, the best thing you can do is do a good job on your thesis and complete your Masters degree. Doing your thesis on a topic of his choice does not increase your chances of being his PhD student, and may decrease your chances because you aren't demonstrating independent judgment.

Both Masters and PhD students should do the work to pick their own topic. (Narrowing down my dissertation topic has been a multi-year exercise -- working part-time.) As a Masters student, you don't have to break new ground or advance the state of the art. But, by picking a topic that is at the state of the art, you demonstrate that you understand, in general, where the state of the art is.

Instead of asking some professor to hand you a topic, you should investigate why picking a topic is hard for you. Do you lack ideas? Do you understand what qualifies as a good idea? Do you have trouble selecting from alternative ideas? Once you've pinpointed the problem, you can ask your adviser or anyone else for help on this aspect of the problem.