Müller's First Superconductor, or Why I Want to Pull My Hair Out Every Time Someone Mentions LK-99

In the summer of 2023, a preprint from a South Korean team claimed to demonstrate a room-temperature, ambient-pressure superconductor called LK-99. The internet exploded. Stock prices moved. Physicists around the world raced to replicate the result. Within weeks, the consensus was clear: LK-99 is not a superconductor. The Meissner effect demonstration turned out to be a ferromagnetic artifact; the resistance drop was caused by a copper sulfide impurity phase. The story was over almost before it began.

And yet the episode left me exhausted in a specific way — not because of the failed replication, which is normal science, but because of the commentary surrounding it. The same errors, the same misconceptions, the same mythology about superconductivity was being recycled, unchanged, from every previous "breakthrough." So let me back up to 1986 and try to explain what actually happened, what it means, and why room-temperature superconductivity is genuinely hard.

Bednorz, Müller, and the First High-Temperature Superconductor

Before 1986, the record critical temperature (Tc) for superconductivity was around 23 K (−250 °C), held by the compound Nb₃Ge. This was achieved in 1973 and had not moved substantially in over a decade. Most theorists believed the BCS (Bardeen–Cooper–Schrieffer) theory of phonon-mediated Cooper pair formation set a practical ceiling around 30–40 K. Superconductivity, for all practical purposes, required liquid helium cooling — expensive, inconvenient, and impractical for most applications.

Georg Bednorz and K. Alex Müller at IBM Zurich were working on a class of materials called cuprates — copper-oxide ceramics that were regarded by most of the community as poor conductors, certainly not promising superconductor candidates. Müller had a hunch, based on a different physical mechanism (Jahn-Teller polarons rather than conventional phonons), that cuprates might be different. In 1986 they published results showing superconductivity at 35 K in lanthanum barium copper oxide (La-Ba-Cu-O). They received the Nobel Prize in Physics the following year — one of the fastest Nobel awards in history, reflecting how significant the discovery was recognized to be.

What made this remarkable was not just the temperature record, but the mechanism. BCS theory, which had successfully explained all known superconductors since 1957, predicted that high-phonon-frequency, strongly-coupled materials would have the highest Tc. Cuprates violated this model. Within months, Paul Chu's group at Houston pushed Tc to 93 K in YBa₂Cu₃O₇ (YBCO) — above the boiling point of liquid nitrogen (77 K). Liquid nitrogen is cheap, widely available, and easy to work with. This was a genuine revolution.

The Mythology Begins

And here is where the trouble started, in 1987 and continuing to this day. The discovery of cuprate superconductors with Tc above 77 K led immediately to headlines proclaiming that room-temperature superconductivity was imminent — maybe five years away, maybe ten. The logic seemed obvious: if Tc jumped from 23 K to 93 K in a single year, surely it would reach 300 K (room temperature) within a decade.

This reasoning ignored two things. First, the jump from 23 K to 93 K was not incremental progress on a smooth curve — it was a new mechanism operating in a new class of materials. The mechanism behind cuprate superconductivity is still not fully understood, despite nearly 40 years of intense research. It is almost certainly not conventional BCS phonon coupling. The leading candidates involve spin fluctuations, charge density waves, or some form of resonating valence bond state — none of which are fully worked out. You cannot extrapolate from a mechanism you do not understand.

Second, Tc did not keep rising. After the initial explosion of cuprate discovery in 1987–1988, the record for Tc under ambient pressure plateaued around 133–138 K (in mercury-based cuprates, discovered in 1993). That record held for over two decades.

What High-Temperature Superconductivity Actually Requires

Room-temperature superconductivity (let's say Tc > 273 K at ambient pressure) would require either:

• A completely new pairing mechanism operating at energy scales ~10× higher than any known mechanism, or
• An extension of existing mechanisms (cuprate, hydrogen-rich compounds, etc.) to conditions that do not require cryogenic cooling or extreme pressure.

The hydrogen-rich superconductors (LaH₁₀, H₃S, and related compounds) have pushed record Tc to ~250–260 K — tantalizingly close to room temperature. But these materials require pressures of 150–200 GPa, far beyond what any practical application can sustain. They are scientifically fascinating but technologically useless unless someone figures out how to stabilize their structure at ambient pressure, which is a completely unsolved problem.

Cuprates, meanwhile, remain the practical workhorse. YBCO and BSCCO (bismuth strontium calcium copper oxide) are used in MRI machines, particle accelerator magnets, power cables in a handful of pilot projects, and experimental fusion reactor designs. They require liquid nitrogen cooling, which is a real cost and engineering burden. But they work. They are real technology.

Why LK-99 Generated Such Excitement

The LK-99 claim had several features that made it especially viral:

• Room temperature and ambient pressure — both simultaneously, which is the holy grail.
• Simple synthesis from relatively common materials (lead apatite with copper substitution).
• A dramatic video showing a sample partially levitating above a magnet, which superficially resembles Meissner effect levitation.
• Multiple independent groups seemingly replicating the resistance drop within days.

Each of these turned out to have a mundane explanation. The levitation was due to ferromagnetism, not the Meissner effect — a ferromagnet also repels from a magnetic field. The resistance drop was traced to a Cu₂S impurity phase that undergoes a well-known metal-insulator transition around 330 K. The "multiple replications" were of the synthesis procedure, not of the superconducting properties. Once careful groups measured resistivity vs. temperature on samples without the Cu₂S impurity, no anomaly was found.

The Pattern That Repeats

LK-99 followed a pattern that has repeated several times since 1987: an exciting claim, rapid but sloppy replications, media frenzy, and eventual refutation. The same pattern played out with the Schön affair (2002, fabricated data), with various organic superconductor announcements, and with the Dias room-temperature superconductor claims (2020, 2023) that are currently under active investigation for data manipulation.

Each cycle has the same structure: the extraordinary claim is seized upon by people who want it to be true, the expert skeptics are dismissed as conservative or jealous, and the eventual refutation comes weeks or months later, buried in technical papers that the general public never reads. The next cycle begins with the public's memory reset.

What makes me want to pull my hair out is not the failed claims themselves — those are normal in science. It is the ritual re-enactment of the same misunderstandings: that Tc is on a smooth upward trajectory, that room temperature is "almost there," that the condensed matter physics community is incompetent for not having solved this yet, that some garage inventor with the right intuition can do what decades of Nobel laureates could not.

What Would Real Progress Look Like?

A genuine room-temperature ambient-pressure superconductor discovery would require:

1. Reproducible synthesis with a well-characterized crystal structure showing no known impurity phases that could explain the observations.
2. Zero resistance measured by a standard four-probe technique on multiple samples in multiple labs, with careful exclusion of alternative explanations.
3. True Meissner effect — complete expulsion of magnetic flux from the bulk material below Tc, distinct from ferromagnetic or paramagnetic effects.
4. Critical field and critical current measurements consistent with superconducting behavior.
5. Independent replication by at least three groups with no connection to the original authors.

LK-99 failed on essentially all of these. The hydrogen-rich superconductors pass all of them — but at pressures that make them impractical.

Müller's Legacy

K. Alex Müller died in January 2023, a few months before the LK-99 episode. His actual achievement — the discovery that a completely unexpected class of materials (copper oxide ceramics) could superconduct at temperatures above liquid nitrogen boiling point — was one of the most surprising results in 20th-century condensed matter physics. It created an entire field, employed thousands of researchers, and led to real applications that are operating today.

It did not lead to room-temperature superconductivity. The mechanism is still not fully understood. The record Tc at ambient pressure has barely moved from 133 K since 1993. These are facts, not failures — they reflect the genuine difficulty of the problem.

The next time someone sends you a link about a new room-temperature superconductor, the correct response is patient skepticism: wait for independent replication, look for Meissner effect data, check whether the authors have ruled out known artifact mechanisms. The history of this field is a graveyard of exciting announcements. The real breakthrough, if it comes, will survive scrutiny. Everything else is noise.