Does product marketing or marketing (marcomm) create content in your company (case studies, one-pagers, sales decks, whitepapers, etc.)?

It is different in different companies but you will most likely see the content divison as follows - 

Product Marketing content: Product focused, long-form, strategic, longer shelf life, consumed by sales (in addition to customers), not all content PMMs do is technical or semi-technical but between content and product marketing, product marketing would be responsible for technical content.

Examples: Sales collaterals, whitepapers, customer case studies (jointly with content team), ROI studies, product messaging, data sheets, Analyst deck (jointly with product managers), Relase marketing

Content Marketing content: High velocity, Short-form, engaging, interactive, time sensitive, focus on likeability

Examples: Tweets, Customer testimonials, press releases (jointly with PMM if the presss release is about a launch), infographics, blog posts, content supporting brand campaign

Core content especially early stages of market establishment - Brochure/At-a-glance, blogs, can all comes from product marketing. Though if you do a detailed messaging brief -- a content writer can also help out to create enough volume for demand gen. PMM's should ideally spend more time with sales in the early stages and even go out fo customers. 

Later stage when you have enough knowledge, customer inputs, producing more heavier pieces - thought leadership also can come from PMM. Its a good way to brand product leaders in the company. 

PR team should also be able to help to secure articles in popular journals. 

Product marketing or content marketing teams. Content marketing tends to be more often responsible for high-velocity content such as daily blogs and social media. More strategic pieces like product briefs/datasheets and white papers are more likely come from a product marketer.

I would think of marcom as the PR team.

I have worked with almost 5 companies in my 6+ years of career as a product marketer. I was the one who owned content and is responsible to gather data for case studies, define a template, write and publish them. Further work on to promote it to get leads.

One thing that I have seen is that a case study doesn't convey a lot. So, I started converting the data into solution documents which are usually an ebook that conveys the entire story with a set of screenshots. 

From the solution documents, we received more leads as compared to a single page case study.

Yes, we do create case studies, check-lists, customer success stories.

As marcomm teams, we talk to our existing & potential customers on a regular basis. Hence, understanding their pain points, speaking their language, and engaging with them becomes second nature to us.

Also, as a start-up/bootstrapped company, division of responsibilities is not always possible. So it is a good opportunity for any product manager/marketer to be involved with the production of BOFU/consideration stage content.

In my career, I have always seen Product Marketing creating content. Product Management and solution architects are also contributing to this content but majority of the thought leadership comes from Product Marketing. 

For Case Studies, it is a mix-bag. The templates and the positioning (that needs to be emphasized) is something that product marketing owns. The specifics can come from sales or customer success team memebrs.