Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session Y55: Magnetization and Spin Dynamics IV: Optomagnetic PhenomenaRecordings Available
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Sponsoring Units: GMAG Chair: Ezekiel Johnston-Halperin, Ohio state University Room: Hyatt Regency Hotel -Adler |
Friday, March 18, 2022 8:00AM - 8:12AM |
Y55.00001: What Can Near-Zero-Field Magnetoresistance Tell Us about Defects in Semiconductors? Stephen J Moxim, Fedor V Sharov, Patrick M Lenahan We show, for a technologically significant case, that near-zero-field magnetoresistance (NZFMR) offers similar analytical power to that of electrically detected magnetic resonance (EDMR) for studying metal-oxide-semiconductor field effect transistor (MOSFET) reliability. NZFMR has significant practical advantages over EDMR in experimental simplicity. NZFMR is used to track the generation of interface trapping centers in Si MOSFETs during accelerated breakdown studies. The technique successfully identifies the Pb0 and Pb1 dangling bond centers via hyperfine interactions with 29Si atoms hosting some of the dangling bonds. NZFMR also provides information about charge capture kinetics at these interface defect sites. The kinetics are explored using the bipolar amplification effect measurement, the theory of which has recently been significantly advanced [1]. |
Friday, March 18, 2022 8:12AM - 8:24AM |
Y55.00002: Effects of spin dynamics on photocarrier relaxation in multiferroic Eu0.75Y0.25MnO3 revealed by optical pump-THz probe spectroscopy Yue Huang Understanding and control of the antiferromagnetic order in multiferroic materials on an ultrafast time scales is a longstanding area of interest, due to its potential applications in magnetic data storage and ultrafast magnetoelectric switching. We present an optical pump-THz probe study of spin and photocarrier dynamics in multiferroic Eu0.75Y0.25MnO3. We found a localized spin excitation, triggered by the ultrafast switching of superexchange interactions on Mn2+ and Mn4+ sites, that decayed within tens of picoseconds with strong temperature dependence. More interestingly, an acceleration of electron-hole recombination developed below the Neel temperature (47 K). This is likely due to enhanced recombination in the A-type AFM state, when the electron spins are aligned in the same plane, without hopping along c axis. Additionally, after 1.5 eV excitation of d-d transitions, we did not observe any obvious changes in the electromagnon modes. Overall, the observed fundamental optomagnetic processes can shed light on ultrafast control of magnetism in multiferroics and photoinduced phase transitions. |
Friday, March 18, 2022 8:24AM - 8:36AM |
Y55.00003: Ultrafast EUV Spectroscopy of Ferromagnetic Multilayers Peter C Johnsen, Sinead A Ryan, Anna Grafov, Christian Gentry, Nathan Brooks, Sheena K Patel, Eric E Fullerton, Henry C Kapteyn, Margaret M Murnane Probing spin dynamics in magnetic materials on their fundamental space, time, and energy scales provides new insights into the strongly-coupled interactions of the spin, charge, and lattice orders. These interactions govern both the equilibrium and excited state dynamics, but they are still poorly understood and thus challenging to control. In past work we showed that ultrafast light induced quenching of the magnetic state has contributions from both spin flips and from spin transport. Here we present ultrafast EUV spectroscopic measurements demonstrating that it is possible to partially suppress laser induced demagnetization in a ferromagnetic thin film by placing a chromium thin film underneath it. The suppression may occur through the reflection of spin currents, which otherwise play an important role in laser induced demagnetization. The suppression of specific demagnetization channels may be a useful tool for tailoring ultrafast magneto-optic interactions. |
Friday, March 18, 2022 8:36AM - 8:48AM |
Y55.00004: Investigation of spin pumping across FeGaB – BiSb interface at two different time scales Vinay Sharma, Weipeng Wu, Prabesh Bajracharya, Quang To, Anthony Johnson, Anderson Janotti, Garnett W Bryant, Lars Gundlach, Matthias Benjamin Jungfleisch, Ramesh C Budhani 3-D topological insulators (TI) with large spin Hall conductivity have emerged as potential candidates for spintronic applications [1]. Here, we report spin to charge conversion in bilayers of amorphous ferromagnet (FM) Fe78Ga13B9 (FeGaB) and 3-D TI Bi85Sb15 (BiSb) activated by two complementary techniques: spin pumping and ultrafast spin-current injection. The spin pumping parameters derived from inverse spin Hall effect measurements are consistent with the results of femtosecond light-pulse induced THz emission, successfully verified using theoretical calculations of spin Hall conductivity of BiSb thin films based on tight binding model. Our results suggest that these first-time measurements and theory of spin dynamics from ~ 10 GHz to several THz in a simple but novel and scalable TI-FM interface provide a promising platform for creating novel spin orbit torque devices. |
Friday, March 18, 2022 8:48AM - 9:00AM |
Y55.00005: Time-resolved measurements of the magnetism induced by the inverse Faraday effect in non-magnetic metals Víctor H Ortiz, Richard Wilson, Luat T Vuong The inverse Faraday effect is an optomagnetic phenomenon that describes the ability of circularly polarized light to induce magnetism in solids. The inverse Faraday effect has potential applications for the development of magnetic recording, quantum computation and spintronic technologies. However, significant gaps in understanding about the effect persist, such as what material properties govern the magnitude of the effect. In this work, we measure by time-resolved magneto-optic Kerr effect measurements of the magnetic moment induced when circularly polarized light irradiates a non-magnetic metal. We measure this inverse Faraday effect in Cu, Pd, Pt, W, Ta and Au for a laser wavelength of 783 nm. We observe that irradiation of these metals with circularly polarized light induces circular dichroism. This nonlinear magneto-optical response to circularly polarized light is an order of magnitude larger in bcc W than other metals, e.g. Pt, Au, or α-phase W. Our results provide insight into what material properties govern the inverse Faraday effect in metals. |
Friday, March 18, 2022 9:00AM - 9:12AM |
Y55.00006: Theory of inverse Faraday effect for non-magnetic materials Shashi B Mishra, Sinisa Coh We have formulated the theory for the linear (absorptive) inverse Faraday effect in non-magnetic metals with bulk inversion symmetry. We point out the importance of using a degenerate time-dependent perturbation theory, as these metals have doubly degenerate band structure even when spin-orbit is present. The degeneracy in these non-magnetic metals is present due to their inversion symmetry in the bulk. We studied the inverse Faraday effect in Au, Pt, Ta, W, Cu, and Pd using first-principles electronic structure calculations. We use the Wannier interpolation scheme to speed up convergence with respect to the sampling of the electron band structure. |
Friday, March 18, 2022 9:12AM - 9:24AM |
Y55.00007: Emergent chiral interaction and ultrafast optical generation of antiferromagnetic spin spirals Sumit Ghosh, Frank Freimuth, Olena Gomonay, Stefan Blügel, Yuriy Mokrousov Ultrafast optical manipulation of magnetic order is one of the most sought after technology for their potential application in the next generation memory devices. The theoretical understanding of underlying physics is however is still under the mist. In this presentation we present a hybrid quantum-classical approach which allows us to reveal the intertwined dynamics of electronic and magnetic degrees of freedom for several picoseconds with a resolution of femtoseconds. Using this method we successfully demonstrate how one can generate a chiral magnetic structure from a collinear antiferromagnetic chain with an ultrafast laser. Our results show that it is possible to generate such chiral structure even in absence of any spin orbit coupling. We show that the necessary chiral interactions are generated out of equilibrium with the laser. We also demonstrate that the chirality of the end configuration can be tuned with the laser parameter as well as the material parameters. We successfully show that the process is non-thermal in nature and quite robust against thermal fluctuation. |
Friday, March 18, 2022 9:24AM - 9:36AM |
Y55.00008: Element Selectivity Ultrafast Demagnetization Dynamics of hybrid Stoner-Heissenberg magnetic alloys Mohamed F Elhanoty, Olle Eriksson, Oscar Grånäs, Olof Karis, Ronny Knut, Susmita Saha Laser induced ultra-fast magnetization dynamics (LIUMD) has been demonstrated to be an excellent way to manipulate the spin and orbital moments of magnetic elements onfemtosecond time scales. Manipulation of the demagnetization amplitude and the corresponding time scale in an element specific way, for multi-component systems, is of fundamental interest to further engineer the LIUMD technique. The method holds promise to significantly change the future of spintronics and information technology in general. However, the interplay between various degrees of freedom in LIUMD of magnetic alloys is intricate due to the competition between different mechanisms and processes. Wedemonstrate the role of spin-orbit coupling (SOC) on the demagnetization of Pd and theinfluence of the optical inter-site spin transfer (OISTR) mechanism of FePd3, and provide via a microscopic picture of LIUMD in this system. Its element resolved magnetization dynamics is obtained by applying the state-of-the-art time-dependent density functional theory (TDDFT). We have also found optical routes in which Fe to demagnetizes before or after Pd in FePd3 providing the fastest way to selectively engineer the demagnetization dynamics in alloys that is desirable for the spintronics technology. |
Friday, March 18, 2022 9:36AM - 9:48AM |
Y55.00009: Exploring Spin Dynamics for Post-Moore Microelectronics with Exascale Modeling Zhi (Jackie) Yao, Revathi Jambunathan, Prabhat Kumar, Andrew J Nonaka The post-Moore's law era has seen unprecedented prosperity of electronic microdevices harnessing novel wave-material interactions beyond conventional single-phase materials. However, gaining an in-depth understanding of the interaction between the waves and materials has been difficult because of the inherent disparity in time and length scale and the lack of effective modeling techniques. |
Friday, March 18, 2022 9:48AM - 10:00AM |
Y55.00010: Qualitatively different injection locking behavior of distinctly different spin Hall nano-oscillator modes Mona Rajabali, Ahmad Awad, Jinjin Yue, Mykola Dvornik, Roman Khymyn, Mohammad Zahedinejad, Himanshu Fulara, Johan Åkerman, Afshin Houshang Spin Hall nano-oscillators (SHNOs) can sustain a number of different auto-oscillating modes [1-3], among which, the solitonic spin wave (SW) bullet can exhibit a finite power threshold to injection locking [4]. Here, we study injection locking of three distinctly different SW modes (edge mode, interior mode, and bullet) in a single 150 nm wide Pt(5 nm)/NiFe(5 nm) SHNO, observed individually by varying the applied field conditions, and find that the bullet indeed exhibits a pronounced threshold whereas the two non-soliton modes do not. We also find that both the bullet and the interior mode show a square dependence of the locking range on injected power while the edge mode locking range is linear in injected power. Theoretical models for these observations will be discussed. |
Friday, March 18, 2022 10:00AM - 10:12AM |
Y55.00011: Quantum trajectories with a large frequency shift in magnetic resonance force microscopy Vladimir I Tsifrinovich, Gennady P Berman Quantum trajectories with a large frequency shift in |
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