SKM 2023 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 47: Quantum-Critical Phenomena
TT 47.4: Vortrag
Donnerstag, 30. März 2023, 10:15–10:30, HSZ 204
Quantum criticality on a compressible lattice — Saheli Sarkar, •Lars Franke, Nikolas Grivas, and Markus Garst — Institut für Theoretische Festkörperphysik, Karlsruhe, Germany
It is a long standing result in the theory of classical criticality that a second order phase transition when coupled to a compressible lattice will become first order if the Larkin-Pikin criterion[1] is satisfied. More recently the extension of these results to quantum criticality has sparked the interest of the community[2,3]. However, until now a detailed analysis of a microscopic theory describing a quantum phase transition on a compressible lattice and its implications for the nature of the phase transition as well as the consequences for the lattice has been missing. Here we provide this calculation for a Lorentz-invariant φ4-theory with quadratic coupling to strain and analyse it using renormalization group (RG) methods to one-loop order. We find that both critical and phonon velocity flow with RG leading to an additional fixed point where the phonons have a renormalized dynamical exponent. Furthermore, our results show that the quantum version of the Larkin-Pikin criterion[2] holds, but even when the criterion is not satisfied a structural instability can still occur, if the coupling is large enough.
[1] A. Larkin and S. Pikin, Sov. Phys. JETP 29, 891 (1969)
[2] P. Chandra, P. Coleman, M. A. Continentino, and G. G. Lonzarich, Phys. Rev. Res. 2, 043440 (2020)
[3] A. Samanta, E. Shimshoni, and D. Podolsky, Phys. Rev. B 106, 035154 (2022)