Talk:Type-II superconductor

It is not customary to describe type II superconductors as having two different Tc's. In fact, it is not customary to think Tc to be a field dependent quantity; usually it is treated as a constant of the material. Usually Tc is thought be at H=0, and Hc(T) is thought to be a temperature-dependent quantity. —Preceding unsigned comment added by 128.8.139.78 (talk) 00:46, 21 May 2008 (UTC)

phase diagram

An H-T diagram for type-2 and type 1 would clarify the distinction. Rod57 (talk) 07:21, 12 June 2008 (UTC)

I've linked to an external diagram until I can find or make a public domain one. Rod57 (talk) 13:22, 2 September 2008 (UTC)

It is incorrect to describe Type II superconductors as having two transition temperatures, they have two critical fields that meet at the same Tc as the external magnetic field goes to zero. I agree that a phase diagram would help. —Preceding unsigned comment added by 134.69.56.178 (talk) 22:27, 20 February 2009 (UTC)

Mixed state and Penetration depths

Ginzburg–Landau_theory#Coherence_Length_and_Penetration_Depth seems to contradict/differ "In a Type-II superconductor, the coherence length is smaller than the London penetration depth, " if the G-L penetration depth is the same as the London penetration depth. Is the London pd obsolete since G-L theory ? and was there a coherence length before G-L theory ? Rod57 (talk) 13:02, 16 October 2008 (UTC)

Definition

The definition needs clarification. How can the transition be gradual when a material either has genuinely zero resistance or it doesn't? I have a PhD in physics (in an unrelated part of the subject) and still don't get this. —Preceding unsigned comment added by 86.53.69.150 (talk) 00:28, 13 March 2010 (UTC)

Adding "Type III"

Hi, I feel that given my own discoveries as well as those by Profs. Esquinazi, Prins and others that it is time to add "Type III" or electron-hole aka bipolaron superconductivity as a theory.

My own analysis suggests that Pb doped into graphite using an organic solvent can indeed superconduct at 281K, Joe Eck has also no less than 24 room temperature materials ie >0C >273.15K and others have similar results.

The theory seems to be that under certain conditions holes can behave like antielectrons in terms of their charge and this is actually how transistors work. Under special conditions they can "pair up" and induce a supercurrent in a conductor such as graphite which can persist and in fact is totally different in nature to Types 1 and 2 (conventional) and occurs at very high temperatures. As the binding energy is much higher they can persist up to the melting point of the lattice so in silicon this would be >550C and in metallic glass even higher.

The crucial condition seems to be absence of oxygen as this seems to be where the solvent helps. Newly prepared graphite exhibits the effect, once only and as soon as exposed to air the effect dissipates.

Kind regards, Andre de Guerin — Preceding unsigned comment added by 88.81.159.167 (talk) 09:35, 7 November 2014 (UTC)

In general, no such addition will take place until reliable sources have published them. Note that reliable sources means more than just believable, there are severe constraints on what meets Wikipedia standards for sourcing - follow the link given to read up on those constraints. Tarl N. (discuss) 18:32, 5 February 2020 (UTC)

Still working on the paper. I did notice something intriguing, and circulated a copy of my findings to some folks also working on similar devices. Seems that complex metal alloys also show signs of resistance drop near 4C (277K) and it is not clear why. — Preceding unsigned comment added by 91.190.161.223 (talk) 20:54, 23 February 2020 (UTC)

Section "Flux pinning"

I think that the section "Flux pinning" is misleading: "flux pinning" means that the vortices are pinned in space inside of the superconductor. The levitating superconductor (above a permanent magnet), as shown in a popular demonstration experiment, indeed requires Flux pinning, but the magnet is not "flux pinned".--Terphys (talk) 11:41, 4 November 2019 (UTC)