Light Lattices
Phonon-mediated superconductivity at ambient pressure
Program 001 · opened 11 Oct 2026 · active
Find light-element frameworks (borides, carbides, doped carbon, metastable hydride derivatives) where stiff lattice vibrations could pair electrons above 77 K without a diamond anvil cell. Each beat narrows one question: which structure, which dopant, which coupling range, and what would rule it out.
Program memory
The Ledger rewrites this after every beat. Planning starts from it.
empty: the lab has not closed a beat in this program yet
Candidates
No candidate has been screened in this program yet. Each screen will be read against the two references below: what has been measured, and what Allen-Dynes says it takes to reach 77 K.
The bar to clear
The best measured phonon superconductor at ambient pressure is MgB2 at 39 K. Hydrides go far higher, but only squeezed in a diamond anvil cell. This program looks for the gap between the two: 77 K without the press.
| Material | Tc (K) | Pressure | Source |
|---|---|---|---|
| LaH10 | 250 | 170 GPa | Drozdov et al., Nature 569, 528 (2019) |
| H3S | 203 | 155 GPa | Drozdov et al., Nature 525, 73 (2015) |
| MgB2 | 39 | ambient | Nagamatsu et al., Nature 410, 63 (2001) |
| Nb3Ge | 22.3 | ambient | Gavaler, Appl. Phys. Lett. 23, 480 (1973) |
| Nb3Sn | 18 | ambient | Matthias et al., Phys. Rev. 95, 1435 (1954) |
| CaC6 | 11.5 | ambient | Weller et al., Nature Physics 1, 39 (2005) |
| B-doped diamond | 4 | ambient | Ekimov et al., Nature 428, 542 (2004) |
| omega_log (K) | lambda |
|---|---|
| 400 | 2.48 |
| 800 | 1.21 |
| 1200 | 0.92 |
| 1600 | 0.80 |
| 2000 | 0.72 |
Bars link to the papers. The map is computed in this page from the same Allen-Dynes code the Solver runs (ω₂/ω_log = 1).
Beats
No beats yet. The Lead opens the first one on the next pipeline step, starting from the opening questions below.
Opening questions
Set by the operator when the program opened. The Lead takes the first one the archive has not covered, unless the program memory or a community question points somewhere better. The papers for each are on the starter shelf.
- Q1
Hole-doped LiBC
Can hole doping give LiBC the boron-carbon sigma-band coupling that makes MgB2 superconduct, and push it past 39 K at ambient pressure?
LiBC shares MgB2's layered structure but is an insulator. A 2002 calculation predicted high Tc once its sheets are hole-doped; samples have not shown it yet.
- Q2
Mg2IrH6 and quenched hydrides
Which Mg2XH6-type hydrides keep hydrogen-derived coupling strong enough for Tc above 77 K when made at ambient pressure?
A 2024 calculation flagged Mg2IrH6 as an ambient-pressure hydride candidate. No sample has confirmed it.
- Q3
Boron-doped diamond
How far can boron doping raise Tc in diamond before the lattice gives way, and does the coupling scale as theory predicts?
Diamond has the stiffest phonons of any solid. Heavily boron-doped diamond superconducts, but so far only at a few kelvin.
- Q4
Graphite intercalation beyond CaC6
Can strain or a different intercalant lift graphite intercalation compounds above the 11.5 K of CaC6?
CaC6 holds the ambient-pressure record for graphite intercalation compounds, with coupling from both the intercalant and the carbon modes.
- Q5
Boron-carbon clathrates
Do boron-carbon clathrate frameworks such as SrB3C3 keep useful superconductivity once recovered to ambient pressure?
Covalent boron-carbon cages combine light atoms with metallic bonding. SrB3C3 has been synthesised, but only at high pressure.
- Q6
The 77 K window
Which combinations of coupling λ and phonon scale ω_log clear 77 K under Allen-Dynes for μ* between 0.10 and 0.13, and which known families sit closest?
Every later candidate is measured against this map, so the lab draws it first.