2025-02-19 ミシガン大学
＜関連情報＞
- https://news.umich.edu/magnetic-switch-traps-quantum-information-carriers-in-one-dimension/
- https://www.nature.com/articles/s41563-025-02120-1
- https://pubs.acs.org/doi/10.1021/acsnano.2c07316
磁気秩序による準1次元励起子のクーロン相関と微細構造の制御 Controlling Coulomb correlations and fine structure of quasi-one-dimensional excitons by magnetic order
M. Liebich,M. Florian,N. Nilforoushan,F. Mooshammer,A. D. Koulouklidis,L. Wittmann,K. Mosina,Z. Sofer,F. Dirnberger,M. Kira & R. Huber
Nature Materials Published:19 February 2025
DOI:https://doi.org/10.1038/s41563-025-02120-1
Abstract
Many surprising properties of quantum materials result from Coulomb correlations defining electronic quasiparticles and their interaction chains. In van der Waals layered crystals, enhanced correlations have been tailored in reduced dimensions, enabling excitons with giant binding energies and emergent phases including ferroelectric, ferromagnetic and multiferroic orders. Yet, correlation design has primarily relied on structural engineering. Here we present quantitative experiment–theory proof that excitonic correlations can be switched through magnetic order. By probing internal Rydberg-like transitions of excitons in the magnetic semiconductor CrSBr, we reveal their binding energy and a dramatic anisotropy of their quasi-one-dimensional orbitals manifesting in strong fine-structure splitting. We switch the internal structure from strongly bound, monolayer-localized states to weakly bound, interlayer-delocalized states by pushing the system from antiferromagnetic to paramagnetic phases. Our analysis connects this transition to the exciton’s spin-controlled effective quantum confinement, supported by the exciton’s dynamics. In future applications, excitons or even condensates may be interfaced with spintronics; extrinsically switchable Coulomb correlations could shape phase transitions on demand.
バルクのファンデルワールス層状磁石CrSBrは準1次元物質である The Bulk van der Waals Layered Magnet CrSBr is a Quasi-1D Material
Julian Klein,Benjamin Pingault,Matthias Florian,Marie-Christin Heißenbüttel,Alexander Steinhoff,Zhigang Song,Kierstin Torres,Florian Dirnberger,Jonathan B. Curtis,Mads Weile,Aubrey Penn,Thorsten Deilmann,Rami Dana,Rezlind Bushati,Jiamin Quan,Jan Luxa,Zdeněk Sofer,Andrea Alù,Vinod M. Menon,Ursula Wurstbauer,Michael Rohlfing,Prineha Narang,and Marko Lončar
ACS Nano Published: March 16, 2023
DOI:https://doi.org/10.1021/acsnano.2c07316
Abstract
Correlated quantum phenomena in one-dimensional (1D) systems that exhibit competing electronic and magnetic order are of strong interest for the study of fundamental interactions and excitations, such as Tomonaga–Luttinger liquids and topological orders and defects with properties completely different from the quasiparticles expected in their higher-dimensional counterparts. However, clean 1D electronic systems are difficult to realize experimentally, particularly for magnetically ordered systems. Here, we show that the van der Waals layered magnetic semiconductor CrSBr behaves like a quasi-1D material embedded in a magnetically ordered environment. The strong 1D electronic character originates from the Cr–S chains and the combination of weak interlayer hybridization and anisotropy in effective mass and dielectric screening, with an effective electron mass ratio of mXe/mYe ∼ 50. This extreme anisotropy experimentally manifests in strong electron–phonon and exciton–phonon interactions, a Peierls-like structural instability, and a Fano resonance from a van Hove singularity of similar strength to that of metallic carbon nanotubes. Moreover, because of the reduced dimensionality and interlayer coupling, CrSBr hosts spectrally narrow (1 meV) excitons of high binding energy and oscillator strength that inherit the 1D character. Overall, CrSBr is best understood as a stack of weakly hybridized monolayers and appears to be an experimentally attractive candidate for the study of exotic exciton and 1D-correlated many-body physics in the presence of magnetic order.
