Sliding after moving

So I'm using a character controller and I want the player to slide around like he's on ice, but I don't know how to do that, so I'd like some help on getting it to work, or if you have suggestions on different things I should use, like a rigidbody, please let me know, here's the code.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;

 [RequireComponent(typeof(CharacterController), typeof(Animator))]
 public class Character : MonoBehaviour
 {

 public CharacterController controller;
 public Transform cam;

 public float speed = 6f;

 public float turnSmoothTime = 0.1f;
 float turnSmoothVelocity;

 [SerializeField]
 private float jumpSpeed, gravity;

 private Vector3 movementDirection = Vector3.zero;
 private Vector3 movementDirection2 = Vector3.zero;

 void Start()
 {
     controller = GetComponent<CharacterController>();
     animator = GetComponent<Animator>();
 }


 void Update()
 {
     float horizontal = Input.GetAxisRaw("Horizontal");
     float vertical = Input.GetAxisRaw("Vertical");
     Vector3 direction = new Vector3(horizontal, 0f, vertical).normalized;

     if (direction.magnitude >= 0.1f)
     {
         float targetAngle = Mathf.Atan2(direction.x, direction.z) * Mathf.Rad2Deg + cam.eulerAngles.y;
         float angle = Mathf.SmoothDampAngle(transform.eulerAngles.y, targetAngle, ref turnSmoothVelocity, turnSmoothTime);
         transform.rotation = Quaternion.Euler(0f, angle, 0f);

         Vector3 moveDir = Quaternion.Euler(0f, targetAngle, 0f) * Vector3.forward;
         controller.Move(moveDir.normalized * speed * Time.deltaTime);
     }

     if (Input.GetButton("Jump") && controller.isGrounded)
     {
         movementDirection.y = jumpSpeed;
     }
     movementDirection.y -= gravity * Time.deltaTime;

     controller.Move(movementDirection * Time.deltaTime);

  }

 }