ConQuMat - TRR360

TRR 360 Seminar:A New Perspective on Correlated Metals: from Concealed Mott Quantum Criticality to Disorder in Heavy Fermi Liquids Louk Rademaker
2025-11-19 14:00 - 15:00 (Europe/Berlin) | Technical University Munich + Zoom
A New Perspective on Correlated Metals: from Concealed Mott Quantum Criticality to Disorder in Heavy Fermi Liquids

Prof. Dr. Louk Rademaker
Université de Genève, Switzerland

The band-structure picture of metals is very successful in many materials where the electron correlations are weak. On the other extreme, when correlations are very strong, one expects interaction-induced insulators – due to Mott localization or symmetry breaking. However, the intermediate regime where correlations are strong but the material remains gapless, harbors many open questions in our understanding of quantum materials.

In this talk, I will give an overview of three aspects of correlated metals. I will discuss the relation between quantum criticality at the Kondo breakdown and in doped charge-transfer insulators like the cuprates. These metal-to-metal transitions can be viewed as exhibiting concealed Mott criticality.

Near a Mott critical point, large effective mass enhancements are observed. The famous Landau relation between mass enhancement and specific heat requires a new sum rule for the temperature-dependence of the electron self-energy.

In such heavy Fermi liquids, the interplay between correlations and disorder cannot be ignored. Inspired by new experiments on organic compounds, we show that contrary to textbooks, the residual resistivity is affected by the mass enhancement.

Venue

TRR 360 Seminar:Experimental prospects on measurement-altered criticality Sara Murciano
2025-11-26 14:00 - 15:00 | Technical University Munich + Zoom
Experimental prospects on measurement-altered criticality
Prof. Dr. Sara Murciano
Université Paris Saclay, France

Quantum critical systems constitute appealing platforms for the exploration of novel measurement-induced phenomena due to their innate sensitivity to perturbations. I will devise a practical scheme for realizing measurement-altered criticality in a chain of Rydberg atoms tuned to Ising and tricritical Ising phase transitions. Projectively measuring a periodic subset of atoms alters quantum critical correlations in distinct ways that one can control via the choice of measured sites and the measurement outcomes. While this protocol relies on post-selection, the measurement outcomes yielding the most dramatic consequences occur with surprisingly large probabilities.

Venue

TRR 360 Seminar:Multiferroic conversionTsuyoshi Kimura
2025-12-17 16:00 - 17:00 | University of Augsburg, Room 242-R
Multiferroic conversion

Prof. Dr. Tsuyoshi Kimura
Department of Applied Physics, University of Tokyo, Japan

Symmetry breaking ascribed to the evolution of an order parameter is one of the most important concepts in materials physics. Representative examples are symmetry breakings in ferroic materials, such as the symmetry breaking of time reversal in ferro-magnets and that of space inversion in ferroelectrics. Recent research developments of multiferroic materials have triggered extensive studies on unconventional ferroic materials such as ferro-toroidic, ferro-axial, and ferro-chiral materials.

In this presentation, we propose the concept of “multiferroic conversion”, which refers to the transformations of ferroic states by combining different ferroic orders. Such conversion occurs, for example, by a deformation of a structural unit in a ferroic material [1] and by the application of external stimuli such as an electric field to a ferroic material [2-5]. We demonstrate several types of multiferroic conversion by observing unconventional optical phenomena, including electric-field-included Faraday effect (from ferro-magnetic-monopolar to ferro-magnetic state) [2], electrogyration (ferro-axial to ferro-chiral) [3], magneto-chiral dichroism (ferro-axial to ferro-magnetic-toroidal) [4], and electric-field-induced nonreciprocal directional dichroism (altermagnetic to ferro-magnetic-toroidal) [5]. The concept of multiferroic conversion will lead to the unconventional functionalities of various ferroic materials.

[1] T. Nagai et al., J. Am. Chem. Soc. 146, 23348 (2024).[2] T. Hayashida et al., Phys. Rev. Research 4, 043063 (2022).[3] T. Hayashida et al., Nat. Commun. 11, 4582 (2020).[4] T. Hayashida et al., Proc. Natl. Acad. Sci. 120, e2303251120 (2023).[5] T. Hayashida et al., Adv. Mater. 37, 241876 (2025).

Venue
