I have heard a few times that having single-author papers is good for your career. I suppose this is because it shows you are capable of producing research on your own. But I wonder if it is a double-edged sword. Say you are early in your career and have only solo papers. Does this also look bad because it suggests you are not good at collaborating?
EDIT: Just to make the perspective clear. Disciplines have varying authorship traditions. In many fields within the sciences, and where I come from, first name in an author list is first author (considered to have contributed most) and collaborative papers are the norm.
Any article where you are first author is "good" for you. Single author articles have become increasingly rare, at least in fields with which I am familiar. The reason is of course that science is rarely done by single persons but rather in groups. Where single author articles are still relatively common are in the form of review articles where a single author can collate and critically assess the state of affairs in for example a subfield.
Going back about 20-30 years, again in the afore mentioned for me familiar fields, single authorship was almost demanded from PhD students and older faculty would basically frown on co-authored articles. Now, single authorship almost carries something odd about it in the sense that one can wonder if the person does not know how to collaborate. The later is of course not a good view to express but it shows how much the views have turned.
So to conclude, writing a well-referenced paper in a high impact journal as first author takes precedence over single or multiple authorship today. I doubt many would look at single authorship as much better than first authorship on a co-authored article today.
It highly depends on the discipline. In the humanities, single-authored papers are (still) often kind of the norm, in the "hard" sciences an exception, and social sciences being somewhere in between (if one can make such a broad generalization anyway). But as a general publication strategy, I think it is always good to aim for a bit of diversity: If most of your papers are probably multi-authored anyway, there is no need to fear that that two or three single-authored papers would give you a reputation of being unable to work in a team. So, if you have a good idea, and if you have the time and ressources to do it on your own, go ahead and write that solo paper. It can be fun, and in terms of reputation, I'd say it is a good chance to communicate: Hey, this is really my work and sth that I really care about, next to all the cool co-authored stuff.
Regardless of what it suggests. Having only solo papers is "suspicious", hiring such a person is therefore risky. When collaborating you are probably going to be able to write more and better papers and your statistics are probably going to look better (depending on how additional authors impact on them). Therefore, when competing for a position, usually collaboration pays off.
At the same time, having some solo paper definitively proves your skills, assuming the quality of the papers is good, they are published in some good venues, etc. Some conferences give "best paper awards", having one of those in a solo paper would definitively prove you as a reliable researcher.
Of course all this depends on the area and what is customary, but I think this summarizes the general idea. And from this you can infer the only point I want to make:
This is not a double-edged sword by any means.
The more papers, the better. In principle no paper is going to hurt you, unless it is wrong, shows no ethics, or similar issues. If you have
x solo papers and
y papers collaborating with other researchers, then having
y+u is only going to be good (for
u greater than 0).
It's a single edged sword, don't worry about publishing, strive for quality and quantity and worry about not-publishing.
So, to make it crisp clear. If you find yourself writing solo papers and publishing only solo papers, go ahead and do it, do it as much as you can and as well as you can. Then try to write some papers collaborating with more people additionally to that (not instead of that).
It is a good practice to have both solo papers and collaborative works. While the latter show your capability of team working, the former demonstrate your self-motivation and ability to publish on your own. Both are top remarks that hiring team would consider important.
- If all papers are co-authored it would sound suspicious that you are heavily dependent on others; this is a bad mark.
- If all papers are solo-authored it would sound suspicious that you are incapable of working with colleagues.
Hence it is the best to have both in your CV.
Beside all the above, in current date, hiring especially in academia does not solely depend on your publication, but on many other factors.
To say that, you should not worry too much about your situation from this point of view.
And it is quite easy to find someone to be added to your authorship list of your paper. Just look around, you will notice many are waiting or willing to do so.