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1. Bulk‐Rashba Effect with Suppressed Spin Relaxation in a Polar Phase of Bi _{1‐ x} In _{1+ x} O ₃

   https://doi.org/10.1002/adma.202504684  

   Kang, Deokyoung; Lu, Xue‐Zeng; Acharya, Megha; Husain, Sajid; Harris, Isaac; Behera, Piush; Lin, Ching‐Che; Banyas, Ella; Smith, Alex; Ricci, Francesco; et al (July 2025, Advanced Materials)

   Abstract The Rashba effect enables control over the spin degree of freedom, particularly in polar materials where the polar symmetry couples to Rashba‐type spin splitting. The exploration of this effect, however, has been hindered by the scarcity of polar materials exhibiting the bulk‐Rashba effect and rapid spin‐relaxation effects dictated by the D'yakonov–Perel mechanism. Here, a polar LiNbO₃‐typeR3cphase of Bi_1‐xIn_1+xO₃withx≈0.15–0.24 is stabilized via epitaxial growth, which exhibits a bulk‐Rashba effect with suppressed spin relaxation as a result of its unidirectional spin texture. As compared to the previously observed non‐polarPnmaphase, this polar phase exhibits higher conductivity, reduced bandgap, and enhanced dielectric and piezoelectric responses. Combining first‐principles calculations and multimodal magnetotransport measurements, which reveal weak (anti)localization, anisotropic magnetoresistance, planar‐Hall effect, and nonreciprocal charge transport, a bulk‐Rashba effect without rapid spin relaxation is demonstrated. These findings offer insights into spin‐orbit coupling physics within polar oxides and suggest potential spintronic applications. 

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2. Anisotropic spin-orbit torque generation in epitaxial SrIrO ₃ by symmetry design

   https://doi.org/10.1073/pnas.1812822116  

   Nan, T.; Anderson, T. J.; Gibbons, J.; Hwang, K.; Campbell, N.; Zhou, H.; Dong, Y. Q.; Kim, G. Y.; Shao, D. F.; Paudel, T. R.; et al (August 2019, Proceedings of the National Academy of Sciences)

   Spin-orbit coupling (SOC), the interaction between the electron spin and the orbital angular momentum, can unlock rich phenomena at interfaces, in particular interconverting spin and charge currents. Conventional heavy metals have been extensively explored due to their strong SOC of conduction electrons. However, spin-orbit effects in classes of materials such as epitaxial 5 d -electron transition-metal complex oxides, which also host strong SOC, remain largely unreported. In addition to strong SOC, these complex oxides can also provide the additional tuning knob of epitaxy to control the electronic structure and the engineering of spin-to-charge conversion by crystalline symmetry. Here, we demonstrate room-temperature generation of spin-orbit torque on a ferromagnet with extremely high efficiency via the spin-Hall effect in epitaxial metastable perovskite SrIrO 3 . We first predict a large intrinsic spin-Hall conductivity in orthorhombic bulk SrIrO 3 arising from the Berry curvature in the electronic band structure. By manipulating the intricate interplay between SOC and crystalline symmetry, we control the spin-Hall torque ratio by engineering the tilt of the corner-sharing oxygen octahedra in perovskite SrIrO 3 through epitaxial strain. This allows the presence of an anisotropic spin-Hall effect due to a characteristic structural anisotropy in SrIrO 3 with orthorhombic symmetry. Our experimental findings demonstrate the heteroepitaxial symmetry design approach to engineer spin-orbit effects. We therefore anticipate that these epitaxial 5 d transition-metal oxide thin films can be an ideal building block for low-power spintronics. 

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3. Driving ultrafast spin and energy modulation in quantum well states via photo-induced electric fields

   https://doi.org/10.1038/s41535-022-00490-2  

   Ciocys, Samuel T.; Maksimovic, Nikola; Analytis, James G.; Lanzara, Alessandra (December 2022, npj Quantum Materials)

   Abstract The future of modern optoelectronics and spintronic devices relies on our ability to control the spin and charge degrees of freedom at ultrafast timescales. Rashba spin-split quantum well states, 2D states that develop at the surface of strong spin-orbit coupling materials, are ideal given the tunability of their energy and spin states. So far, however, most studies have only demonstrated such control in a static way. In this study, we demonstrate control of the spin and energy degrees of freedom of surface quantum well states on Bi 2 Se 3 at picosecond timescales. By means of a focused laser pulse, we modulate the band-bending, producing picosecond time-varying electric fields at the material’s surface, thereby reversibly modulating the quantum well spectrum and Rashba effect. Moreover, we uncover a dynamic quasi-Fermi level, dependent on the Lifshitz transition of the second quantum well band bottom. These results open a pathway for light-driven spintronic devices with ultrafast switching of electronic phases, and offer the interesting prospect to extend this ultrafast photo-gating technique to a broader host of 2D materials. 

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4. Spintronic Terahertz Emission in Ultrawide Bandgap Semiconductor/Ferromagnet Heterostructures

   https://doi.org/10.1002/adom.202201535  

   Comstock, Andrew; Biliroglu, Melike; Seyitliyev, Dovletgeldi; McConnell, Aeron; Vetter, Eric; Reddy, Pramod; Kirste, Ronny; Szymanski, Dennis; Sitar, Zlatko; Collazo, Ramón; et al (October 2022, Advanced Optical Materials)

   Recent successful integration of semiconductors into spintronic THz emitters has demonstrated a new pathway of control over terahertz (THz) radiation through ultrafast demagnetization dynamics. Here, the spintronic THz emission from different ultrawide bandgap (UWBG) semiconductors interfaced with ferromagnets is studied. The authors show that the Schottky barrier in the UWBG semiconductor AlN acts as a spin filter that increases the polarization of the spin current injected from the ferromagnet. Furthermore, the authors show that the two-dimensional electron gas at the interface between Al0.25Ga0.75N and GaN enhances the magnitude of the emitted radiation due to the high spin-to-charge conversion efficiency induced by the Rashba effect that results in a hallmark asymmetry in emission amplitude. The results provide a framework for future engineering of semiconducting/ferromagnet heterostructures for ultrafast communications technologies beyond 5G. 

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5. Composition gradient-enabled circular photogalvanic effect in inogranic halide perovskites

   https://doi.org/10.1063/5.0083187  

   Jia, Ru; Jiang, Jie; Zhang, Lifu; Hu, Yang; Pendse, Saloni; Guo, Yuwei; Shi, Jian (May 2022, Applied Physics Letters)

   Inversion symmetry breaking could lead to the creation of a Rashba–Dresselhauls magnetic field, which plays the key role in spintronic devices. In this work, we propose and develop a composition gradient engineering approach that breaks inversion symmetry into inorganic halide perovskites with strong spin–orbit coupling. We synthesize epitaxial CsPbBr x Cl (3− x ) with Br/Cl composition gradient by a two-step chemical vapor deposition approach. Through optoelectronic measurements, we show the presence of circular photogalvanic effects (CPGEs), evidencing a Rashba-like spin polarized band structure. By spatially resolved photoluminescence spectra, we find that the observed CPGE is likely a cumulative result of inversion symmetry-broken interfaces featured by abrupt and stepwise composition gradient between the pristine and separated daughter phases. Our work suggests an avenue in engineering the spintronic property of halide perovskites for information processing. 

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