Rigidbody.angularDrag

The angular drag of the object.

Angular drag can be used to slow down the rotation of an object. The higher the drag the more the rotation slows down

JavaScript

rigidbody.angularDrag = 10;

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        rigidbody.angularDrag = 10;
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        rigidbody.angularDrag = 10