Spring Data MongoDB: how to implement entity relationships?

The title of this question is quite contradictory since I'm trying to implement relations in a non-relational database... :)

But what I mean is how to define associations between entities in application model classes working with MongoDB.

Working with JPA I often use @ManyToMany or @OneToMany annotations to define relationships between objects. Is there something similar in Spring Data MongoDB?

Studying MongoDB I realized that there are two possible approaches to the association: References and Embedded Data.

Which one is used by Spring Data? Is it possible to configure the association mode?