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 J37: New Probes of Correlated OxidesFocus Live
|
Hide Abstracts |
Sponsoring Units: GMAG DMP DCOMP DCMP Chair: Vidya Madhavan, University of Illinois at Urbana-Champaign |
Tuesday, March 16, 2021 3:00PM - 3:12PM Live |
J37.00001: Direct Imaging of Orbitals in Quantum Materials: ground state and excited states Liu Tjeng, Brett Leedahl, Andrea Amorese, Martin Sundermann, Hasan Yavas, Hlynur Gretarsson, Andrea Severing, Maurits Wim Haverkort Recently we have developed a new experimental method that can make a direct image of the ground state d-orbitals in transition metal compounds [1,2]. The method, s-core-level x-ray Raman or non-resonant inelastic x-ray scattering (s-NIXS), relies on dipole-forbidden transitions which become available when the experiment is carried out with high momentum transfers. New opportunities are opened up for the investigation of the ground state, especially for quantum materials that are too complex to be handled by ab-initio theories. Here we will go one step further and explore the spectroscopy aspect of s-NIXS in order to study the excited states which are most often dominated by many-body atomic multiplet interactions. We will show that we are able to obtain images by which we can identify the orbital character of those excited states. This in turn facilitates the extraction of important energy parameters in correlated materials. |
Tuesday, March 16, 2021 3:12PM - 3:24PM Live |
J37.00002: Acoustic Magnon hybridized with Orbital on Multiferroics Ba2MnGe2O7 Shunsuke Hasegawa, Shohei Hayashida, Shinichiro Asai, Masato Matsuura, Takatsugu Masuda Spin-driven multiferroics is a research field which explores nontrivial phenomena emerged by spin-orbit coupling (SOC). The effect of SOC in quasi-particle spectra has been investigated in high-energy range; electromagnon, hybridization of magnon and phonon, and renormalization of optical magnon. The effect of SOC to acoustic magnon in low-energy range which plays important roles in bulk properties, however, has not been studied. Here we demonstrate that the acoustic magnon in multiferroics Ba2MnGe2O7 [1-3] is hybridized with orbitals by measuring the temperature variations of magnetization curves and neutron scattering spectra. The temperature dependence of the anisotropy energy is scaled not by the spin moment but by the electric polarization. The observation evidences renormalization of orbital effect into a spin-nematic interaction and the hybridized magnon in an emergent field. Our finding exhibits that the spin-flop transition field is a sensitive probe for SOC, which could be a key for search of new magnetoelectric materials. |
Tuesday, March 16, 2021 3:24PM - 4:00PM Live |
J37.00003: Imaging the impact of atomic-scale disorder and temperature fluctuations on antiferromagnetic ordering in iridates Invited Speaker: Ilija Zeljkovic Over the past decade, Ruddlesden-Popper iridates emerged as a versatile playground for investigations of exotic phenomena, such as a doped Mott insulator state, Fermi arcs, density wave instabilities and spin-related orders. We use spin-polarized scanning tunneling microscopy (SP-STM) to visualize spin-resolved modulations arising from the antiferromagnetic (AF) order in doped Mott insulators Sr2IrO4 and Sr3Ir2O7. We find that near insulator-to-metal transition, the long-range antiferromagnetic order melts into a fragmented state with short-range correlations. We investigate the impact of chemical disorder on the distribution of these AF domains to pinpoint a defect most strongly correlated with the domain arrangement. Thermal erasure and re-entry into the AF state leads to a partial spatial reorganization of AF modulations, indicating multiple stable AF configurations at low temperature. Interestingly, regardless of this rearrangement, the AF puddles maintain scale-invariant fractal geometry. Our experiments shed light onto the sensitivity of the AF order to different types of atomic-scale disorder, and reveal its surprising fluidity with thermal cycling. |
Tuesday, March 16, 2021 4:00PM - 4:12PM Live |
J37.00004: Onset of two-dimensional Stoner magnetism in cobalt arsenides Benjamin Ueland, Bing Li, Santanu Pakhira, Aashish Sapkota, Sangeetha Nediadath Sathyanadhan, Toby G Perring, David C Johnston, Robert J McQueeney CaCo1.86As2 is a unique example of a metallic square-lattice system with nearly perfect frustration despite the compound having A-type antiferromagnetic (AF) order below a Néel temperature of TN = 52 K. Our recent neutron diffraction data on Ca(Co1-xFex)2-yAs2 show that the A-type AF order is suppressed past x = 0.12, and here we give results from INS experiments made at T = 6 K on single-crystal samples of x = 0.15. We find diffuse spin fluctuations giving rise to walls of magnetic scattering with similar anisotropy to that found for x = 0, however, the fluctuating moment is extremely weak. A simultaneous analysis of magnetic susceptibility and neutron scattering data shows that the total magnetic moment is gradually reduced with increasing x. This suggests that the development of magnetic order has a Stoner-like mechanism where Fe-doping acts to tune (and decrease) the Stoner parameter UN(EF). This highlights that cobalt arsenides are uniquely frustrated and weakly itinerant magnets. |
Tuesday, March 16, 2021 4:12PM - 4:24PM Live |
J37.00005: Strong fluctuations and itinerant magnetic frustration in a multiorbital model for SrCo2As2 Ana-Marija Nedic, Morten Holm Christensen, Yongbin Lee, Rafael Fernandes, Robert J McQueeney, Liqin Ke, Peter Orth Despite the observation of strong stripe antiferromagnetic fluctuations, the paradigmatic cobalt pnictide metallic magnet SrCo2As2 exhibits an intriguing lack of magnetic order. Minute amounts of substitutions of Co by Ni, corresponding to electron doping, however, induce long-range spiral magnetic order in the metallic magnet. To understand these puzzling observations, we investigate a realistic interacting multi-orbital model for SrCo2As2 that takes both Co d-orbitals and As p-orbitals into account. We find that the static paramagnetic RPA spin susceptibility exhibits a crossover from dominantly ferromagnetic to dominantly stripe antiferromagnetic fluctuations as a function of both doping and modifications of Hubbard to Hund interactions. In agreement with experimental observations, our model shows a clear tendency towards the development of magnetic order under electron doping, while hole doping moves the system further into the paramagnetic regime. By analyzing the orbital character of the leading magnetic fluctuations, our study elucidates the proposed mechanism of itinerant magnetic frustration as the origin of the observed lack of magnetic order. |
Tuesday, March 16, 2021 4:24PM - 4:36PM Live |
J37.00006: Coherent spin dynamic of strongly correlated defects in spin chains. Sylvain Bertaina, Loic Soriano, julian zeisner, Vladislav kataev, Hervé Vezin, Marc Fourmigué, Maylis Orio The quantum coherence of spins is usually studied in highly diluted magnetic ions in a diamagnetic medium. We propose a new paradigm: a non-magnetic defect, like a break in the translational symmetry of Heisenberg’s spin chain, polarized many spins around it. |
Tuesday, March 16, 2021 4:36PM - 4:48PM Live |
J37.00007: Ultrafast Mid Infrared Pump-Optical Kerr Probe of Correlated Mott-Hubbard Antiferromagnets Mustafa G Ali, Kelson Kaj, Varun Ramaprasad, Gufeng Zhang, Xiang Chen, Urban F. P. Seifert, Jingdi Zhang, Kevin A Cremin, Leon Balents, Stephen D. Wilson, Richard Averitt We utilize intense ultrafast mid-infrared (mid-IR) circularly polarized pump pulses to preferentially excite spin degrees of freedom through coherent two-magnon excitation as measured via the magneto-optic Kerr effect using 800 nm pulses. Our previous results [1] on the spin-orbit coupled Mott-Hubbard insulator (MHI) Sr2IrO4 indicate that magnon generation using mid-IR pulses is nearly an order of magnitude more efficient in comparison to above gap doublon generation. To clarify the potential of mid-IR pulses for coherent magnon generation, we are investigating the canonical MHI nickel oxide which serves as a well characterized material for comparison with theoretical predictions [2]. This presentation will provide an update on these experiments with a view towards mode-selective spin excitation in quantum materials. |
Tuesday, March 16, 2021 4:48PM - 5:00PM Live |
J37.00008: Time-Domain THz studies of antiferromagnetic Bi2CuO4 Rishi Bhandia, Tanya Berry, William Phelan, Tyrel McQueen, Peter Armitage The antiferromagnetic insulator Bi2CuO4 has been of research interest due to its unusual crystal structure of staggered CuO_4 plaquettes. While the first synthesis of this compound was reported in 1976, the exact spin structure of the magnetic order that develops below 43.5 K remains a mystery. In addition, recent studies of this compound report the presence of a magneto-electric effect in this material. We present the results of time-domain THz studies of single crystals of Bi2CuO4 grown via the traveling solvent technique in a laser floating zone furnace . |
Tuesday, March 16, 2021 5:00PM - 5:12PM Live |
J37.00009: High-resolution AC Calorimetry Measurement of Honeycomb magnet Na2Co2TeO6 Zhenhai Hu, Yuan Li, Xi Lin AC calorimetry is a steady-state measurement technique capable of detecting small heat-capacity signals and variations. Recently, Na2Co2TeO6 is proposed as a candidate material for realizing the Kitaev-Heisenberg model on a honeycomb lattice, and its low-temperature thermal phase behaviors are currently under exploration. Equipped with a home-made AC calorimetry setup, we have measured the heat capacity of Na2Co2TeO6 single crystals with a resolution that is significantly better than commercial equipment. We find an unexpected small heat-capacity peak at low temperature and in zero magnetic field. |
Tuesday, March 16, 2021 5:12PM - 5:24PM Live |
J37.00010: Magnetoelastic standing waves induced in UO2 by microsecond magnetic field pulses Marcelo Jaime, Rico Schoenemann, George Rodriguez, Dwight Gene Rickel, Fedor Balakirev, Ross McDonald, Jordan Evans, Boris A Maiorov, Charles Paillard, Laurent Bellaiche, Myron B Salamon, Krzysztof Gofryk We performed magnetoelastic measurements of the piezomagnetic antiferromagnet UO2 via the Fiber Bragg Grating method in pulsed magnetic fields up to 150 T generated by a single-turn coil setup. While still insufficient to suppress the robust low temperature magnetically ordered state, we show that the uniquely short timescales of a few micro seconds of the magnetic-field pulse excite mechanical elastic resonances in the sample due to the piezomagnetic coupling. This results in standing-wave magnetoelastic oscillations superimposed on the magnetostriction signal. We compare the resonances with natural resonance frequencies obtained by a resonant ultrasound technique. The piezomagnetic switching behavior of the antiferromagnetic ordering vector below TN=30.5K, which was revealed in a previous study [M. Jaime et al., Nature Communications 8, 99 (2017).] results in an apparent phase shift of π in the lattice oscillations. We further present a model to explain our data. |
Tuesday, March 16, 2021 5:24PM - 5:36PM Live |
J37.00011: High-resolution angle-resolved photomission study of CeSb2 Xiaoxiao Wang, Xiaoyang Chen, Yifei Fang, Xiaobo Jin, Haichao Xu, Rui Peng, Donglai Feng The rare earth compound CeSb2 belongs to a strongly correlated system, and it shows a rich magnetic phase diagram depending on the temperature. And the magnetic transport measurements show the highly anisotropic nature of the magnetization of CeSb2 in the ab-plane. In order to determine the electronic properties of CeSb2, previous study by synchrotron radiation photomission spectroscopy but without angular resolution shows no indication of Kondo-like behavior in the bulk properties. Reexamination of the resonance behavior of Ce 4f by tracking the evolution of Fermi surface and electronic structure is needed. |
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. |
© 2023 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
1 Research Road, Ridge, NY 11961-2701
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700