Email is an important mode of communication both outside and within an organisation. It is fast and efficient as a clear message can be easily delivered. The same is true for emails that are to be sent within a department.
In case the company is hiring new employees, an email can be sent to the HR department for arranging the process to make sure that all aspects are covered and there is no lacking at the end of the day. It is not a cumbersome email in any way.
Start the email by letting the concerned person know that there is a need for new hiring and therefore interviews need to be arranged.
In the second paragraph, let the person know the details regarding the interviews and potential dates for them.
Conclude the email by asking to keep you posted on the arrangements and to ask any questions freely should the need arise.