this code is not working

Question

at first time, success Challenge().
but after logout() always failed.
always false == Request.IsAuthenticated

why? at challenge(), redirect login page but not autheniticated.

if (!Request.IsAuthenticated)
{
HttpContext.GetOwinContext().Authentication.Challenge(
new AuthenticationProperties { RedirectUri = "/Home/Login" },
OpenIdConnectAuthenticationDefaults.AuthenticationType);
}