Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session V10: Fe-based Superconductors -- Theory and ModelingFocus
|
Hide Abstracts |
Sponsoring Units: DMP DCOMP Chair: Brian Andersen Room: BCEC 151B |
Thursday, March 7, 2019 2:30PM - 3:06PM |
V10.00001: Band structure of pnictides: effects of crystal symmetry and pressure Invited Speaker: Vladislav Borisov Even after ten years of intensive studies of iron-based superconductors these remarkable materials still remain enigmatic due to their large structural variety and a complex interplay of magnetism and superconductivity. Recently discovered AeAFe4As4 (1144) pnictides revealed new exciting phenomena, such as the spin-vortex magnetism [1] and pressure-induced half-collapse transitions [2], that originate from the special crystal symmetry. |
Thursday, March 7, 2019 3:06PM - 3:18PM |
V10.00002: DFT+eDMFT study of lattice dynamics in FeSe Ghanashyam Khanal, Kristjan Haule Effect of electron-electron interactions in the high-temperature superconductivity has been one of the challenging issues in condensed matter physics. We study the lattice dynamics of one of the iron-based high-temperature superconductors FeSe using ab-initio Density Functional Theory (DFT)+ embedded Dynamical Mean-Field Theory (eDMFT) functional approach. We found that the electron-electron interaction plays an important role in determining the phonon frequencies of different vibrational modes in this material. The phonon frequencies are in a very good agreement with the experimentally reported values in particular when compared to previously reported DFT results. The agreement extends also in the phonon band structure along with the phonon density of states. |
Thursday, March 7, 2019 3:18PM - 3:30PM |
V10.00003: Quantum Phase Transitions in a Multi-Orbital Hubbard Model for Iron Pnictides Wenjun Hu, Luca Fausto Tocchio, Hsin-Hua Lai, Rong Yu, Federico Becca, Qimiao Si Quantum criticality in iron pnictides was proposed within an effective field theory that contains both antiferromgnetic and nematic order parameters [1,2]. Its proposed realization in P-doped BaFe2As2 has received extensive experimental evidence [3,4]. Here we study this problem within a multi-orbital Hubbard model containing both the Hubbard and Hund’s interactions. We analyze the effect of electron correlations in a non-perturbative way, through a variational Monte Carlo method that is based on a Jastrow-Slater wave function. We study the evolution of the electronic orders as the interaction strength is varied, report evidence for concurrent antiferromagnetic and nematic quantum critical points, and discuss the implications for superconducting pairing. |
Thursday, March 7, 2019 3:30PM - 3:42PM |
V10.00004: Quantum dynamical screening of the local magnetic moments in the different families of Fe-based superconductors Clemens Watzenböck, Martin Edelmann, Daniel Springer, Andreas Hausoel, Giorgio Sangiovanni, Alessandro Toschi The formation of localized magnetic moments and their dynamical screening represents one of the crucial ingredients of the physics of correlated metals. Their theoretical treatment is, in fact, crucial to correctly predict the spectroscopic observations in several important classes of correlated materials [1,2]. In this talk, we investigate [3] the local spin dynamics in different families of Fe-based superconductors by means of realistic dynamical mean-field theory calculations: We compute the dynamic magnetic correlations on the Fe sites both in real frequency and in real time domain. The former allows for a direct comparison with inelastic neutron spectroscopy, explaining the trends observed in the experiments on the different families of Fe-based superconductors. The latter allows to identify the characteristic time scales of the spin dynamics in these materials, which is useful for the interpretation of the discrepancies between different experimental probes, and, in perspective, for the analysis of future non-equilibrium experiments. |
Thursday, March 7, 2019 3:42PM - 3:54PM |
V10.00005: Symmetry analysis of magnetoelastic couplings in the Fe-based superconductors William Meier, Andreas Kreyssig, Paul Canfield Antiferromagnetism (AFM) is a reoccurring theme in the Fe-based superconductors. The stripe-type AFM on the Fe lattice in these compounds is accompanied by a sympathetic orthorhombic distortion of the tetragonal structure. This is not the only kind of magnetoelastic coupling possible between magnetic and structural degrees of freedom. Based on a symmetry analysis of the crystal structures we obtain the symmetry-allowed coupling terms in the Landau free energy. We propose that many of the compounds in this family (including FeSe, BaFe2As2 and CaKFe4As4) will develop a periodic structural modification when a magnetic field is applied to the AFM ordered phase. This should produce additional Bragg peaks which could provide a sensitive indicator of the AFM order under extreme conditions, such as in high pressure cells. |
Thursday, March 7, 2019 3:54PM - 4:06PM |
V10.00006: Simple transport models for the temperature-dependent linear magnetoresistance of pnictide and cuprate superconductors John Singleton Taken in conjunction with the temperature (T) dependence of the zero-field resistivity, simple transport models invoking e.g., realistic variations in charge-carrier density are shown to be sufficient to explain the linear magnetoresistance and field-temperature resistance scaling recently observed in high-temperature pnictide and cuprate superconductors. Hence, though the T-linear zero-field resistance is a definite signature of the "strange metal" state of high-temperature superconductors, their linear magnetoresistance and its scaling need not be; instead they may merely be signatures of disorder. Straightforward experimental tests of these assertions are proposed. |
Thursday, March 7, 2019 4:06PM - 4:18PM |
V10.00007: Pairing symmetry and topological surface state in iron-chalcogenide superconductors Lun Hu, Congjun Wu The gap function symmetries remain an important question in the study of iron-based superconductors. |
Thursday, March 7, 2019 4:18PM - 4:30PM |
V10.00008: Theory for quasiparticle interference in the presence of spin-orbit coupling in strongly electron-doped iron-based superconductors Jakob Böker, Pavel Volkov, Peter Hirschfeld, Ilya Eremin Motivated by recent experimental reports on sizable spin-orbit coupling (SOC) and a sign-changing order-parameter |
Thursday, March 7, 2019 4:30PM - 4:42PM |
V10.00009: Broken time-reversal symmetry in s+is and s+id states of multi-band superconductors: vortices, skyrmions, domain walls and spontaneous magnetic fields. Egor Babaev, Julien Garaud, Mihail Silaev, Alberto Corticelly The recent experiments on Iron-based superconductors reported two interesting sitiuations: the formation of s-wave superconducting state in Ba1−xKxFe2As2 that breaks time-reversal symmetry (BTRS) (i.e. the so-called s+is state) and disorder-driven crossover from s+- to s++ state. Both of these situations should be accompanied by unconventional physics that will be discussed in this talk. I will discuss the origin of the spontaneous magnetic fields in the s+is state [1], unconventional topological excitations arising due to BTRS such as domains walls and Skyrmions [2], the breakdown of type-I/type-II dichotomy due to a divergent coherence lengths at the s+- to s+is transition causing the magnetic field penetration length to be intermediate length scale: ξ1<λ< ξ2 [3,4] resulting in vortex clustering, and a rather generic coexistence of the s+- and s++ states near the s+- to s++ crossover [5]. |
Thursday, March 7, 2019 4:42PM - 4:54PM |
V10.00010: Interplay of structural properties and van der Waals forces in presence of magnet disorder in FeSe and FeTe by density-functional theory calculations Felix Lochner, Ilya Eremin, Tilmann Hickel, Jörg Neugebauer We investigate the structural origin of the iron-based superconductors FeSe and FeTe in the presence of several magnetic orders, where we focus on the competition between stripe-type anti ferromagnetism (AFM) and paramagnetic disorder (PM). Here, the PM state is implemented by using the spin-space average approach [1] in combination with constrained magnetic moments for our density-functional calculations (DFT). To predict the correct ground state in respect to the lattice parameters, we use the similarity of the AFM and PM state to transfer the correlations for specific structural properties of the AFM picture to those correlation for the PM approach. |
Thursday, March 7, 2019 4:54PM - 5:06PM |
V10.00011: Anomalous Non-Superconducting Time-Reversal-Symmetry Breaking State in Multicomponent Superconductors Daniel Weston, Egor Babaev Multicomponent superconductors can break time-reversal symmetry, either due to phase frustration in Josephson-coupled superconductors with at least three components, or due to higher-order Josephson coupling in superconductors with at least two components. Beyond mean-field theory, such systems may have an anomalous phase in which time-reversal symmetry is broken despite superconducting order being absent. Models of the aforementioned type have been argued to describe the multiband superconductor Ba1-xKxFe2As2. We report properties of the fluctuation-induced precursory normal state that breaks time-reversal symmetry. |
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