publications - is it good for academic path if I publish too many papers in arxiv

Currently, I am a PhD student from material science and I wish to become a TT professor in the future. When submitting papers, we see an option to submit it in arxiv and it seems to me that the acceptance to the arxiv would probably be much faster than usual journal. I want to ask if publishing articles in arxiv instead of usual journals would make my career less promising or not.... thank you:)

Answer

No, you shouldn't just submit to the arXiv instead of journals.

Articles in the arXiv are not considered published in the traditional sense, and they are not peer reviewed. In fields that use the arXiv, papers are typically submitted there and to a journal (but you can do this only if the journal's policies permit it, so you should check if you aren't sure). The role of the arXiv is then to provide access to preprints before publication and "green open access" to published papers.

You don't have to submit an arXiv paper for publication, and occasionally people use it to distribute papers they don't intend to publish (and for which they aren't looking for publication credit). But you should be careful to avoid getting a reputation for putting mediocre papers on the arXiv.

There have been a few high-profile cases of great arXiv papers that were never published, like Perelman's work on the Poincaré conjecture. However, you can't get away with that when starting an academic career (unless you are revolutionizing your field). If you just submit papers to the arXiv and not to journals or conferences, it will destroy your career. They will count for far less than published papers, and search committees will wonder about all sorts of explanations. Are you profoundly eccentric? Do you have no idea how academic careers work? Are your papers just not good enough for journals? Is there something you are hoping nobody finds out via peer review (e.g., that you plagiarized or rediscovered something already known)? Basically, everyone will make uncharitable negative assumptions, in addition to considering the papers themselves as worth less.

The question you've asked is a perfectly reasonable thing to wonder about, but I find it a little alarming that you've basically proposed career suicide with no indication that your advisor has warned you. This suggests that talking with your advisor more about career issues could be helpful, or attempting to find another mentor if your advisor is not so helpful. Academic career paths can be narrow and demanding, and good advice is essential.