laravel make email not unique code example

Example: check mobile or email in laravel

protected function credentials(Request $request)
        {
          if(is_numeric($request->get('email'))){
            return ['phone'=>$request->get('email'),'password'=>$request->get('password')];
          }
          elseif (filter_var($request->get('email'), FILTER_VALIDATE_EMAIL)) {
            return ['email' => $request->get('email'), 'password'=>$request->get('password')];
          }
          return ['username' => $request->get('email'), 'password'=>$request->get('password')];
        }