Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Y50: Orbital-Selective Correlations in Iron-Based SuperconductorsInvited Live
|
Hide Abstracts |
Sponsoring Units: DCMP Chair: Elbio Dagotto, Tennessee University |
Friday, March 19, 2021 11:30AM - 12:06PM Live |
Y50.00001: Orbital-selective correlations and block magnetism in low-dimensional iron-based superconductors Invited Speaker: Adriana Moreo The discovery of superconductivity in Fe-based two-leg ladder materials under high pressure [1] has opened new directions to improve our understanding of pairing tendencies in iron-based superconductors. Computational calculations of strongly correlated electronic models can be performed with high accuracy in quasi one dimension, including the case of multi-orbital systems. Using numerical techniques, such as DMRG, multi-orbital Hubbard models were studied at various Hubbard and Hund couplings, and electronic densities. We have found clear indications of pairing in slightly doped chains [2] and ladders [3]. The magnetic properties observed in these systems are also rich, including the observation of an ``orbital selective Mott Phase'' in a wide parameter range. This phase is characterized by the formation of magnetic block states where a block of N spins "up" alternate with a block of N spins "down" [4,5,6,7]. We were able to calculate the dynamical spin structure factor and interpret the results in terms of a mixture of acoustic and optical modes [4,6,7] in agreement with neutron scattering experiments. This complex behavior observed in models for the Fe-based superconductors in low dimensions when studied with unbiased techniques indicates that the physics of these materials can hide several surprises. |
Friday, March 19, 2021 12:06PM - 12:42PM Live |
Y50.00002: Orbital selective superconductivity in iron-based superconductors Invited Speaker: Pengcheng Dai Superconductivity in iron-based superconductors emerges from long-range ordered antiferromagnetic phase with nematic order that breaks four-fold rotational symmetry of the underlying lattice. In spite of considerable work over the past decade, much is unclear concerning the microscopic origin of superconductivity and its relationship with magnetism, nematicity, and orbital order. In this talk, I will summarize our recent inelastic neutron scattering studies of iron-based superconductors, focusing on studying the relationship between magnetism, nematic order, and superconductivity. We find that orbital selective magnetic excitations and superconductivity are central to a microscopic understanding of these materials. |
Friday, March 19, 2021 12:42PM - 1:18PM Live |
Y50.00003: Orbital-selective correlation and nematicity in iron-based superconductors Invited Speaker: Rong Yu There is an expanding recognition that orbital-selective electron correlation plays a crucial role in understanding the properties of the iron-based superconductors [1,2]. In this talk, I will survey the theoretical developments on this subject, focusing on the orbital-selective Mott physics [3,4] which has been recently extensively studied, and its influence on the electronic bandstructure. I will then address the interplay between the orbital-selective correlation and electronic nematicity in iron selenide FeSe [5], and more generally, discuss how the nematic order and anisotropic fluctuations are understood in terms of strong electron correlations [6-8]. Implications of these results for the superconductivity will be discussed. |
Friday, March 19, 2021 1:18PM - 1:54PM Live |
Y50.00004: Nematic Fluctuations in an orbital-selective superconductor Fe1+yTe1-xSex Invited Speaker: Jiun-Haw Chu Optimal superconductivity is found in the vicinity of a fully suppressed nematic phase for most families of iron-based high-temperature superconductors, leading to speculation that nematic quantum critical fluctuations enhance or even mediate this superconductivity. While there has been extensive investigation of nematic fluctuations in several families of iron pnictides, much less is known about iron chalcogenides, in particular the family of Fe1+yTe1-xSex. Fe1+yTe1-xSex is special in several regards. It is one of the earliest discovered iron-based superconductors with the simplest crystal structure. Its phase diagram hosts the most complicated evolution of spin dynamics. It is also recognized as the most strongly correlated iron-based superconductors, as seen from the highly orbital dependent band renormalization. In this talk, I will present a systematic study of both B1g and B2g nematic fluctuations in Fe1+yTe1-xSex using the technique of elastoresistivity measurement, which showed that the two nematic fluctuations closely track the corresponding spin fluctuations, confirming the intertwined nature of the two degrees of freedom. I will also discuss the unusual temperature dependence of the nematic susceptibility, which revealed the highly orbital selective nature of the nematic instability, a property that has been long speculated by the theory. |
Friday, March 19, 2021 1:54PM - 2:30PM Live |
Y50.00005: Spin-Orbital-Intertwined Nematic State in FeSe Invited Speaker: Tao Wu In this talk, I would like to discuss our recent progress on understanding the mechanism of electronic nematicity in FeSe superconductor. Through a comprehensive study of 77Se and 57Fe nuclear magnetic resonance (NMR) [1], a nontrivial SOC effect is revealed in the nematic state of FeSe. First, the orbital-dependent spin susceptibility, determined by the anisotropy of the 57Fe Knight shift, indicates a predominant role from the 3dxy orbital, which suggests the coexistence of local and itinerant spin degrees of freedom in the FeSe. Then, we reconfirm that the orbital reconstruction below the nematic transition temperature (Tnem) happens not only on the 3dxz and 3dyz orbitals but also on the 3dxy orbital, which is beyond a trivial ferro-orbital order picture. Moreover, our results also indicate the development of a coherent coupling between the local and itinerant spin degrees of freedom below Tnem, which is ascribed to a Hund’s coupling-induced electronic crossover on the 3dxy orbital. Finally, because of a nontrivial SOC effect, sizable in-plane anisotropy of the spin susceptibility emerges in the nematic state, suggesting a spin-orbital-intertwined nematicity rather than a simple spin- or orbital-driven nematicity. In addition, I will also introduce new progress on high-pressure 57Fe NMR study of FeSe. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700