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);

 }

}

I would have values set for the current x and z velocities, and have it so that if the Axis input is small (or 0) it moves with the current velocities minus 0.1 (or a suitable value)