CathInfo.com

"As I demonstrate in this volume with copious quotations from De Romano Pontifice, St. Robert Bellarmine, explains in precisely what qualified sense a manifestly heretical pope can be said to be judged and deposed, i.e., declared to ‘be deposed’ (esse depositus) by himself, rather than be deposed from the papacy by the authority of the Church (deponi posse). As Pope Gregory XVI explains (in the passage quoted below), such a judgment would not be made against the 'Pope recognized as such, but only against the person, who was before adorned with papal dignity'."

Kramer, Paul. To deceive the elect: The catholic doctrine on the question of a heretical Pope (p. 132). Kindle Edition.

"St. Robert Bellarmine teaches most explicitly (De Romano Pontifice, lib. ii. cap. xxx) that it is heresy by its very nature, (ex natura haeresis), which severs the heretic from the Church, and causes the immediate loss of ecclesiastical office: «Thenceforth, the Holy Fathers teach in unison, that not only are heretics outside the Church, but they even lack all Ecclesiastical jurisdiction and dignity ipso facto.» In De Ecclesia Militante Bellarmine says it is demonstrated by the testimony of the Fathers who teach with a common consensus that those who are outside the Church have no authority or jurisdiction in the Church; and quoting St. Augustine, Bellarmine declares that all heretics and all schismatics have departed from the Church. Salza & Siscoe desperately attempt to interpret the Fathers as teaching that the heretic’s severing himself from the Church and the subsequent loss of office does not take place without the authority of the Church, but result from an ecclesiastical censure or judgment of the crime. Bellarmine, in his refutation of the Fourth Opinion utterly destroys that argument: «Nor does the response which some make avail, that these Fathers speak according to ancient laws, but now since the decree of the Council of Constance they do not lose jurisdiction, unless excommunicated by name, or if they strike clerics. I say this avails to nothing. For those Fathers, when they say that heretics lose jurisdiction, do not allege any human laws which maybe did not exist then on this matter; rather, they argued from the nature of heresy. Moreover, the Council of Constance does not speak except on the excommunicates, that is, on these who lose jurisdiction through a judgment of the Church. Yet heretics are outside the Church, even before excommunication, and deprived of all jurisdiction, for they are condemned by their own judgment, as the Apostle teaches to Titus; that is, they are cut from the body of the Church without excommunication, as Jerome expresses it.»"

Kramer, Paul. To deceive the elect: The catholic doctrine on the question of a heretical Pope (pp. 229-230). Kindle Edition.

There is no indication of a "material" pope in any of the passages above.

So because Kramer doesn't mention it, it doesn't exist?  I've already explained where the principles come from Bellarmine's (and others') explanation of the distinction between the designation/election to office (material, by the due representatives of the Church) and the bestowal of papal authority upon the candidate (formal).  Election itself does not formally communicate authority (unlike with the principles of "democracy").  So the distinction is not only there but it's common sense.  You can argue about whether it applies to a heretical pope, i.e. whether a pope loses the election/designation (material aspect of office) or just the formal authority (as sedeprivationists and Fr. Chazal argue), but the distinction is quite real.  Pretty much everything that exists outside of God and the angels has a material aspect and a formal aspect.  That lies at the core of Aristotelian/Thomistic ontology.

I hold with the sedeprivationists (and with John of St. Thomas, Cajetan, and Fr. Chazal) that there must be some role for the Church to play, since it doesn't suffice for Fr. Cekada's "Aunt Helen" to wake up one morning and declare a pope to be a non-pope.  Straight SVism doesn't have a backstop to prevent this chaotic principles ... as John of St. Thomas explained in developing his approach to the question.  In fact, we're seeing the chaos play out right now.  Fr. Kramer, Bennyvacantists, and Sedevacantists all hold that Bergoglio is not the Pope.  But SSPX, Conciliar conservatives, etc. hold that Bergoglio is the pope.  How is this chaos resolved?  Who decides?  Who has the authority to impose the correct reality on the consciences of all Catholics?