How to freeze rotation of rigidbody?

Hi guys,

I want to rotate my player while pressing vertical arrows. I use Quaternion.Euler. Everithing works fine but when I release the arrow, the rotation goes back to it´s origin position to 0. I want to set the rotation by using keybord arrows and freeze that position even when I release the arrows.
Which function instead of Euler sould I use in this case?

Here is my script:

private float tilt = 15f;

void FixedUpdate ()
{
   float moveVertical = Input.GetAxis ("Vertical");
   rigidbody.rotation = Quaternion.Euler (0.0f, moveVertical * tilt, 0.0f);
}

Probably this way?

private float tilt = 15f;
float moveVertical;
void FixedUpdate ()
{
if (Input.GetAxis ("Vertical") != 0)
  moveVertical = Input.GetAxis ("Vertical");
rigidbody.rotation = Quaternion.Euler (0.0f, moveVertical * tilt, 0.0f);
}

I figure it out:

     private float tilt = 15f;
     float moveVertical;
     void FixedUpdate ()
     {
     if (Input.GetAxis ("Vertical") != 0)
     {
        moveVertical += Input.GetAxis ("Vertical") * speed * Time.DeltaTime;
        moveVertical = Mathf.Clamp (moveVertical, -tilt, tilt);
     }
     rigidbody.rotation = Quaternion.Euler (0.0f, moveVertical, 0.0f);
     }