Is the pseudogap temperature T* a thermodynamic phase transition? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title · changed
Revision 1: Is the pseudogap temperature T* a thermodynamic phase transition
Revision 2: Is the pseudogap temperature $T*$ a thermodynamic phase transition?
Plain
If the pseudogap is a true phase, crossing its boundary should leave a mark in heat capacity, as freezing does for water; no such mark has been clearly seen.
Precise · changed · core
Revision 1: In a clean hole-doped cuprate (YBa2Cu3O6+x or HgBa2CuO4+d), determine whether the free energy is nonanalytic along T*(p): resolve a specific-heat or thermal-expansion anomaly at T* matching the symmetry breaking claimed by polarized neutron scattering, torque magnetometry and polar Kerr rotation, or bound $\Delta C/T$ below the value required by a mean-field transition with the claimed order parameter. An answer is a detected singularity with its exponent, or such a bound.
Revision 2: In a clean hole-doped cuprate (YBa2Cu3O6+x or HgBa2CuO4+d), determine whether the free energy is nonanalytic along $T*(p)$: resolve a specific-heat or thermal-expansion anomaly at $T*$ matching the symmetry breaking claimed by polarized neutron scattering, torque magnetometry and polar Kerr rotation, or bound $\Delta C/T$ below the value required by a mean-field transition with the claimed order parameter. An answer is a detected singularity with its exponent, or such a bound.
Settled by
High-resolution calorimetry or thermal expansion through $T*$ on crystals in which torque or neutron onsets are measured on the same piece.
Kind
well-posed
Answer type
yes-no
References
(empty)
Literature status
contested
Status note · changed
Revision 1: Resonant ultrasound (2013) found an elastic anomaly along T*(p), and torque magnetometry (2017) and polarized neutron data indicate symmetry breaking near T*, but no calorimetric anomaly at T* has been resolved and the neutron results are disputed.
Revision 2: Resonant ultrasound (2013) found an elastic anomaly along $T*(p)$, and torque magnetometry (2017) and polarized neutron data indicate symmetry breaking near $T*$, but no calorimetric anomaly at $T*$ has been resolved and the neutron results are disputed.
Posed since
(empty)

Decisions