Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session D68: Emergent phenomena in oxide interface due to broken symmetry and interface interactionsInvited
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Sponsoring Units: GMAG Chair: Jian Liu, University of Tennessee Room: Room 420 |
Monday, March 6, 2023 3:00PM - 3:36PM |
D68.00001: Proximity induced ferromagnetism in the spin-orbit semimetal SrIrO3 Invited Speaker: Dirk Fuchs The 5d iridium-based transition metal oxides (TMOs) of the Ruddlesden-Popper series Srn+1IrnO3n+1 have gained huge and broad interest because of the strong spin-orbit coupling in these compounds favoring new or exotic quantum states. This has resulted in one of the most active and competitive front of condensed matter research. In contrast to the 3d TMOs, the electron-electron correlation strength is however generally too small in the 5d TMOs to yield e.g. ferromagnetism, limiting the field of practical applications of these materials. Recently, we succeeded to produce a ferromagnetic (FM) state in the spin-orbit semimetal SrIrO3 (SIO) by proximity effect in contact with an FM insulator, LaCoO3 (LCO) [1]. The FM state of SIO was selectively probed by electrical transport in SIO/LCO thin film heterostructures. A large intrinsic and positive anomalous Hall effect (AHE) appears for T ≤ 100 K and indicates magnetic ordering. The AHE shows unusually large coercivity below about 40 K, very likely caused by a strong pseudo-spin lattice coupling. The anisotropic magnetoresistance (AMR) displays four-fold magneto-crystalline anisotropy with in-plane <110>pc magnetic easy axis. In addition, the use of SrTiO3 as a gate material allows for a non-volatile electric control opening new routes towards a more efficient spin manipulation. The proximity induced FM state in SIO is significantly enhanced for positive gate voltage Vg and strongly suppressed for Vg < 0. The anomalous Hall conductivity sAHE and Hall angle QHall varies strongly with Vg and can be increased by about 600%. |
Monday, March 6, 2023 3:36PM - 4:12PM |
D68.00002: Interfacial charge transfer in atomically thin SrIrO3 / SrRuO3 heterostructures Invited Speaker: Kyle M Shen Metallic interfacial quantum materials are most readily detected at the interface between two insulating constituents by probes such as electrical transport. However, when either material is conducting, transport techniques become insensitive to interfacial properties. To overcome these limitations, we employ angle-resolved photoemission spectroscopy and molecular beam epitaxy to reveal the electronic structure, charge transfer, doping profile, and carrier effective masses in a layer-by-layer fashion for the interface between the Dirac nodal-line semimetal SrIrO3 and the correlated metallic ferromagnet SrRuO3. Through comparisons with first-principles theory calculations, we determine that electrons are transferred from the SrIrO3 to SrRuO3, with an estimated screening length of 3.2± 0.1 Å. In addition, we find that metallicity is preserved even down to a single SrIrO3 layer, where the dimensionality-driven metal-insulator transition typically observed in SrIrO3 is avoided because of the strong hybridization of the Ir and Ru t2g states. |
Monday, March 6, 2023 4:12PM - 4:48PM |
D68.00003: Breaking Spin and Exchange Symmetries in Compositionally Complex Oxide Heterostructures Invited Speaker: Zac Ward The way that materials behave can simply be thought of as a response to what the electrons in the material are doing. Controlling the atoms' arrangement to one another in a crystal lattice changes where the electrons reside and how they interact with one another. If we can continuously control atomic compositions and structural relationships between the constituent elements, we can then manipulate functionality with unprecedented precision. I will describe our efforts to open previously inaccessible lattice symmetries and compositional phase spaces in strongly correlated quantum materials by means of entropy-assisted synthesis of high entropy oxides. I will provide examples from our recent works that demonstrates how continuous control of symmetry opens new avenues to manipulate magnetic anisotropy and how compositional complexity can be used to design dynamic spin frustration by tailoring local degeneracies. We will close with a discussion of how shifting local variances in spin and exchange coupling types while maintaining position symmetries provides exciting opportunities for designing novel Griffiths phases or quantum many-body systems with tunable critical behaviors. |
Monday, March 6, 2023 4:48PM - 5:24PM |
D68.00004: Emergent magnetic and topological phenomena in (111) pyrochlore iridate thin films Invited Speaker: Xiaoran Liu During the past decade, quantum materials with nontrivial band topology have become a focal theme in condensed matter physics. In this thriving field, great efforts have been recently made for the experimental discovery of correlated topological semimetals. Pyrochlore iridates R2Ir2O7 (R is a rare-earth ion) being the very first magnetic Weyl semimetal (WSM) candidate, direct demonstrations of its characters with the peculiar "all-in-all-out" antiferromagnetic (AFM) ordering has remained elusive thus far, due to limitations in both available materials and probing techniques. |
Monday, March 6, 2023 5:24PM - 6:00PM |
D68.00005: Emergent electronic and magnetic properties of spatially confined ruthenates Invited Speaker: Jiandi Zhang Heterostructures of complex transition metal oxides are known to induce extraordinary quantum states that arise from broken symmetry and other discontinuities at interfaces. One of the currently existing issues is to reveal the origin of these emergent states. In this talk, I will focus on some unusual behaviors of the interfaces and thin films/heterostructures of ruthenates. Emergence of unusual, thickness-dependent ferromagnetic and transport properties in ultrathin CaRuO3 films is found through a unique insertion of a single isovalent SrO layer (referred to as "?-doping"). While bulk CaRuO3 is metallic and nonmagnetic, films thinner than or equal to ~15-unit cells (u.c.) are insulating though still nonmagnetic. However, ?-doping to middle of such CaRuO3 films induces an insulator-to-metal transition and ferromagnetism with unusual magnetoresistive behavior. The results highlight the delicate nature of magnetic instability in CaRuO3 and subtle effects that can alter it, especially the role of A-site cation in electronic and magnetic structure additional to lattice distortion. On the other hand, the insertion of SrRuO3 monolayer into SrTiO3 films results in nonmagnetic and insulating character. the results indicate that the observed non-stoichiometry is the cause of the observed loss of metallicity and ferromagnetism in the monolayer SrRuO3. |
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