Concept · physics
Phase transitions beyond melting and boiling
4 studies1 discoveryEvidence last moved Sep 27, 2026
A phase transition is a qualitative change in a system's state as a control parameter is tuned. This page covers electronic Lifshitz transitions (changes in Fermi-surface topology) driven by magnetic field or by light, a magnonic Dicke superradiant transition in a magnetic crystal, and classical cavity nucleation in a stretched liquid.
Students usually meet phase transitions as changes in density or symmetry, like melting. These studies show transitions can also be changes in electronic topology or collective mode mixing, and can be tuned by field or ultrafast light rather than temperature.
Studies
4
Findings
4
4 supporting · 0 challenging · 3 qualifying citations
Open tensions
1
Latest change
Concept page published
Phase transitions beyond melting and boiling
Currently
What we know
- A magnetic field can push an electronic band feature through the Fermi level and change the surface's order.
- Light can trigger a transient Lifshitz transition without heating the crystal through a structural change.
- Coupled magnons can realise a Dicke-type superradiant transition that is forbidden for ordinary photons.
- First-order transitions start by crossing a nucleation barrier that depends on how far into the metastable region the system is.
Largest unresolved question
The two Lifshitz studies differ in drive (steady magnetic field at millikelvin vs femtosecond light pulse), material and probe (surface STM vs photoemission), so they illustrate the same kind of transition but cannot be directly compared quantitatively.
Common misconceptions
Every phase transition involves heating or cooling.
Here a magnetic field of about 11 T drove a Lifshitz transition, a 1.8 T field ended a superradiant phase, and a light pulse produced a transient Lifshitz transition while the lattice stayed at about 71 K.
The Dicke superradiant transition is impossible, because of the no-go theorem.
The no-go theorem applies to the photonic version with a diamagnetic A-squared term; the magnon-based model derived for ErFeO3 lacks that term, and the data showed the expected critical signatures.
Related
Claim ledger
What the evidence shows
Drawn from 4 studies in this library. Mix labels say which citation roles are present; they are not a strength score. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope.
A magnetic field can push an electronic band feature through the Fermi level and change the surface's order.
Scanning tunnelling microscopy below 100 mK showed a van Hove singularity moving from about 4.5 mV down through the Fermi energy near 11 T, a field-induced Lifshitz transition, accompanied by a stripe charge order that grew with field.
- How does a magnetic field reshape electrons at a ruthenate surface?— Surface-layer result; authors stress the surface differs from the bulk.
Light can trigger a transient Lifshitz transition without heating the crystal through a structural change.
Time-resolved photoemission showed new electron pockets appearing on the Fermi surface after a light pulse and vanishing within about a picosecond, with the pocket bottom crossing the Fermi level by 17 ± 7 meV, while the lattice stayed far below its structural transition temperature.
- Can a laser flash change a metal's Fermi surface topology?— One material; simulations are frozen-lattice and qualitative.
Coupled magnons can realise a Dicke-type superradiant transition that is forbidden for ordinary photons.
In ErFeO3 at 2 K, the system left a superradiant phase at a critical field of 1.8 T: the upper mode's frequency kinked and the lower mode softened below the measurable range; at 10 K neither mode showed critical behaviour.
- Can magnets show the long-sought superradiant phase transition?— Full mode softening is inferred, and the mean-field model has six fitted parameters.
First-order transitions start by crossing a nucleation barrier that depends on how far into the metastable region the system is.
Molecular dynamics of a stretched Lennard-Jones liquid gave free-energy curves with a maximum at a critical cavity size, as classical nucleation theory predicts, with barrier and critical size shrinking as the tension increased.
Debates
Tensions and limits
Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes.
The two Lifshitz studies differ in drive (steady magnetic field at millikelvin vs femtosecond light pulse), material and probe (surface STM vs photoemission), so they illustrate the same kind of transition but cannot be directly compared quantitatively.
The two Lifshitz studies differ in drive (steady magnetic field at millikelvin vs femtosecond light pulse), material and probe (surface STM vs photoemission), so they illustrate the same kind of transition but cannot be directly compared quantitatively.
- How does a magnetic field reshape electrons at a ruthenate surface?
- Can a laser flash change a metal's Fermi surface topology?
Study Role Design N Population Outcome How does a magnetic field reshape electrons at a ruthenate surface? Supports OtherScanning tunnelling microscopy and quasiparticle interference imaging below 100 mK in magnetic fields up to 13.5 T, compared with DFT and ARPES Measurements on cleaved single crystals; no sample count given, results confirmed in a second STM and on a Ti-doped sample. High-purity single crystals of bilayer strontium ruthenate (surface layer) Tunnelling spectra, quasiparticle interference dispersions, and topographic charge order as a function of magnetic field Can a laser flash change a metal's Fermi surface topology? Supports OtherPump-probe time-resolved multidimensional photoemission on a cooled crystal, combined with time-dependent DFT+U simulations No sample N; bulk Td-MoTe2 crystals cleaved and measured at 30 K across pump-probe delays Bulk crystals of the type-II Weyl semimetal Td-MoTe2 Time evolution of the Fermi surface and energy position of the γ electron pocket after infrared excitation
PaperFren reads this as a limit on how far one study travels — different assays, populations, or outcomes — not a forced fight between papers.
Timeline
How understanding moved
Study years are when the paper was published. Evidence edits are dated changes to this page's claims. Explanations are when PaperFren added a Discovery — not a claim that the science happened that day.
2026
- Slowly sheared grains follow rigidity percolation, but faster flow shifts the exponents
Concept page published
Phase transitions beyond melting and boiling
Change log
What changed
Dated edits to this page's evidence: studies added or removed from a claim, claims added or withdrawn, and new explanations tagged here. Rewordings are not listed.
- Concept page published
Papers
4 studies in this library bear on Phase transitions beyond melting and boiling, ordered by citations.
- Can a laser flash change a metal's Fermi surface topology?
A femtosecond infrared pulse briefly pushes an empty electron pocket in MoTe2 below the Fermi level, changing its Fermi surface topology for under a picosecond.
- Can magnets show the long-sought superradiant phase transition?
In the magnetic crystal ErFeO3, one coupled spin mode drops toward zero frequency while the other kinks at the same field, the signature of a Dicke superradiant phase transition.
- How does a magnetic field reshape electrons at a ruthenate surface?
A magnetic field pushes a special point in the surface electron bands of a ruthenate through the Fermi level, changing the Fermi surface and switching on stripe-like charge order.
- How much energy does it take to open a bubble in stretched liquid?
Averaging the work from many fast, non-equilibrium simulations recovers the full energy barrier for opening a nanoscale cavity in a stretched liquid, even under mild conditions that ordinary simulations cannot reach.
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The two Lifshitz studies differ in drive (steady magnetic field at millikelvin vs femtosecond light pulse), material and probe (surface STM vs photoemission), so they illustrate the same kind of transition but cannot be directly compared quantitatively.
Ask PaperFren about Phase transitions beyond melting and boiling
Study this conceptflashcards and short-answer questions
What is a Lifshitz transition and how have experiments driven one without changing temperature?
A Lifshitz transition is a change in the topology of the Fermi surface, for instance when a band edge or van Hove singularity crosses the Fermi energy. STM imaging showed a van Hove feature crossing the Fermi level near 11 T of applied field. Time-resolved photoemission showed electron pockets appearing briefly after a light pulse, with the lattice kept below its structural transition. In both cases the control parameter was field or light, not temperature.
Explain the role of the nucleation barrier in a first-order transition, using simulation evidence.
Forming a new phase costs surface energy but gains bulk energy, so free energy first rises then falls with nucleus size, giving a barrier at the critical size. Simulations of cavity formation in a stretched liquid reproduced this maximum. Stretching the liquid further lowered both the barrier and critical size, making nucleation more likely. The caveat is that the cavity was forced open rather than forming spontaneously.