No, you should not be able to do that. Android apps are not permitted to write to system directories.
You should probably create this directory within your app's private storage area. Generally it is best to discover the path of that from Java (don't hardcode it) and then pass it through to the native side.
Depending on your needs for the file, the ExternalStorage might also be an option, especially during development where you might need to easily modify it manually - though keep in mind that others things will be able to change it there, too. Again, you should determine the path on your particular device in Java and then pass that through to the native code.