Session E40: 60 Years since BCS and 30 Years since Woodstock

Phil Anderson's Magnetic Ideas in Superconductivity

In Philip W. Anderson's research, magnetism plays a special role, providing a prism through which other forms of collective behavior and broken symmetry, particularly superconductivity can be examined. This talk covers Phil Anderson's work on superconductivity, from his pseudo-spin formulation of BCS theory, to the Anderson Higg's mechanism and the RVB theory of cuprate superconductivity. Material will be drawn from various discussions that took place at the conference celebration of Anderson’s 90 th birthday in 2013.   

The Woodstock of Physics: The Hyped Future Then (1987)\textellipsis The Actual Situation Now (2017).

In late January, 1986, Georg Bednorz stayed after work at the IBM Zurich Research Laboratory to measure the temperature dependence of the conductivity of a copper oxide perovskite whose preparation had recently been published by the CNRS group at the University of Caen. He had recognized that the Caen material composition matched that of the ``Jahn-Teller-Bipolaron'' high-temperature superconductivity pairing model speculated previously by his IBM mentor, Alex Mueller. One of his samples revealed trace superconductivity near 20-25 K, a stupendous result at the \underline {time}$^1$. In the late fall of 1986, Paul Chu and his collaborators at U. Huston and Alabama detected a sharp transition at 91 K in the same perovskite family. Subsequently, confirmation pandemonium ensued throughout the planet, resulting in the gathering termed ``The Woodstock of Physics'' convened at the New York Hilton the second week of March, 1987. Would HTSC thus embody the long sought ``energy deliverance of mankind?'' Not yet, despite obtaining materials reaching ambient pressure Tc's of 135 K, and after many successful demonstrations of \underline {power applications}$^2$ of these discoveries worldwide over the last three decades. \underline {Why not}$^3$ and when will its promise be fulfilled? That's the subject of this presentation.\\ \\$[1]$http://w2agz.com/Publications/Opinion\%20\&\%20Commentary/W2AGZ/Cold\%20Facts/2016/PMG\%20article\%20 from\%20cold\_facts\_vol32\_no1\_2016.pdf\newline $[2]$http://w2agz.com/Publications/Science\%20\&\%20Technology/W2AGZ/09b\%20(2010)\%20Superconductivity\%20in\%20 Power\%20Applications,\%20Wroclaw\%20ICEC-ICMC.pdf\newline $[3]$ http://w2agz.com/Publications/Opinion\%20&\%20Commentary/W2AGZ/PowerMag/Upbraiding-the-Utilities\_4242.pdf   

The Current Experimental Status of the High Tc Problem

Over 50,000 experimental papers have been published since 1987 on the copper oxide (cuprate) high Tc superconductors. In this talk, I will attempt to summarize the experimental properties that we presently understand and those that we don't yet understand. I will not speculate on the ``unknown unknowns'', although some examples of these have appeared during the past 30 years of research. I may also present a few slides about the status of iron-based superconductors, the other major class of unconventional high Tc materials.   

Why did it take over 40 years from the experimental discovery of superconductivity to the BCS theory and will it take this long to understand the high Tc superconductors?

This year marks the 60th anniversary of the publication of the BCS theory of superconductivity. One of the seminal theories of the past century, the BCS theory followed 46 years after the discovery of superconductivity by Kamerlingh Onnes. This year also marks 31 years since Bednorz's and Muller's discovery of the high Tc cuprates. In this talk I've been asked to discuss why it took 46 years between Onnes's discovery of superconductivity and the BCS explanation and comment on where we are after 31 years with respect understanding the high Tc cuprates.   

Pressing Hydrogen into an Atomic Metallic Phase: Implications for Superconductivity:

One of the great challenges to condensed matter physics is transforming solid molecular hydrogen to the atomic metallic phase predicted by Wigner and Huntington over 80 years ago. We have succeeded in producing metallic hydrogen in a diamond anvil cell at a pressure of 495 GPa. This is the highest pressure ever achieved on hydrogen and we shall discuss the measures taken to achieve this holy grail of high pressure physics. Metallic hydrogen was predicted to be a high temperature superconductor, years ago by Ashcroft; modern calculations predict the possibility of critical temperatures higher than room temperature. Recent high pressure experiments on hydrogen-rich hydrogen sulfide found a critical temperature above 200 K. The future will tell us if the pure substance, atomic metallic hydrogen, will finally achieve the goal of room temperature superconductivity.