Special Session CK-6
Magnetoeletrics and Multiferroics: Advances in Materials, Devices and Applications
ABSTRACTS
CK-6:IL32 Artificial van der Waals Multiferroics with Electrically Reversible Spin Splitting
E.Y. TSYMBAL, University of Nebraska-Lincoln, Department of Physics and Astronomy, Lincoln, NE, USA
Van der Waals (vdW) assembly has recently become a powerful tool to create two-dimensional (2D) materials with novel properties, often distinct from those of the individual layers. Especially interesting is polar stacking of vdW layers that breaks inversion symmetry, giving rise to switchable out-of-plane polarization in systems that are not intrinsically ferroelectric. Here, we propose to apply such polar stacking to vdW antiferromagnets to create artificial 2D multiferroics exhibiting non-relativistic spin splitting (NRSS) in their electronic band structure. Based on the spin-space group symmetry approach, we identify several representative vdW antiferromagnets which exhibit different types of NRSS when stacked into a polar bilayer. We demonstrate that NRSS can have both altermagnetic and non-altermagnetic origins and elucidate symmetry requirements for NRSS to be switchable by electric polarization. Potentially, the electric polarization switching of NRSS in AFM polar bilayers may be more practical for device applications than spin-orbit torque induced switching of the AFM order parameter.
CK-6:L37 (Sm0.25Ho0.25Yb0.25Lu0.25)FeO3 High Entropy Multiferroic Ceramics
XIANG MING CHEN, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
(Sm0.25Ho0.25Yb0.25Lu0.25)FeO3 high-entropy ceramics were prepared and characterized. Dense ceramics with single phase structure in space group Pbnm were obtained, in which the homogeneous distribution of the rare-earth elements was determined. The suppressed leakage current was achieved, and a high dielectric peak with strong frequency dispersion was detected. Weak ferromagnetic behavior was determined in changed from pinched hysteresis to saturated hysteresis with decreasing temperature, while the Mr increased monotonically. Moreover, a linear magnetoelectric coefficient up to 0.75 mV/cm Oe was achieved in the present high-entropy ceramics.
CK-6:IL38 Spin-orbit-coupling in Ferroelectric vdW Heterostructures
JUNLING WANG, Department of Physics, City University of Hong Kong, Kowloon Tong, Kowloon, Hong Kong SAR
Multiferroic materials, such as BiFeO3, allow for the electric-field control of magnetization because of their magnetoelectric coupling effect. They have been studied extensively for the rich underlying physics and potential applications in spintronic devices. However, research on conventional multiferroic materials have encountered serious obstacles, e.g., small coupling coefficients of Type-I multiferroics and low temperature/high conductivity of Type-II multiferroics. Recent developments on 2D ferroelectric materials open a new paradigm in the field. Their unique layered structure allows for the coexistence of switchable polarization and high conductivity, even superconductivity. In this talk, I will discuss the unique properties of 2D ferroelectric materials and the opportunities they brought in term of electric-field control of spin and magnetization.
[1] “Sub-nanosecond Polarization Switching with Anomalous Kinetics in vdW Ferroelectric WTe2“, Yinxin Bai, Zhichao Yu, Zeyu Guan, Junjiang Tian, Chuanshou Wang, Xiaodong Yao, Yihao Yang, Yunlin Lei, Jingbo Xu, Chenhao Liu, Jinlong Zhu, Yuchen Tu, Shengchun Shen, Hongjun Xiang, Xiaoguang Li*, Changsong Xu*, Junling Wang*, Nature Communications 16, 7221 (2025); [2] Chuanshou Wang, Lu You*, David Cobden, Junling Wang*, Towards two-dimensional van der Waals ferroelectrics, Nature Materials 22, 542 (2023).
CK-6:IL40 Electric-field Control of Skyrmions in Multiferroic Heterostructures
YONGGANG ZHAO, Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, China
Skyrmions are topologically protected particle-like spin textures and have potential applications in information storage due to their small size and high mobility. Room-temperature skyrmions in multilayers are promising candidates for the next-generation spintronic devices with high-density, low-power consumption and non-volatility. Electric-field control of skyrmions, such as the strain-mediated electric-field control, has the advantage of ultralow power dissipation. We demonstrate strain-mediated electric-field control of skyrmions, including creation, deformation and annihilation, through magnetoelectric coupling in multiferroic heterostructure [1]. We also show that individual skyrmions on nanodots can be created and deleted by local electric fields in nanostructured multiferroic heterostructures and the control is reversible, nonvolatile and magnetic field-free [2]. Moreover, we explore room-temperature creation and manipulation of individual skyrmion bags in magnetic multilayered disks [3]. Our work will stimulate more research for electric-field control of skyrmions and other spin textures.
[1] You Ba et al., Nature Communciations, 12, 322 (2021). [2] Yutong Wang et al, Phys. Rev. Lett. In revision. [3] Quan Liu et al., Nature Communciations, 16, 125 (2025).
This work was supported by Guangdong Major Project of Basic Research, China (Grant No. 2021B0301030003) and Project of the Ministry of Science and Technology of China (2023YFA1406400)
CK-6:IL42 Terahertz Photovoltaic Effect of Multiferroics
YOUTAROU TAKAHASHI, Quantum-Phase Electronics Center (QPEC) and Department of Applied Physics, The University of Tokyo, Tokyo, Japan
Multiferroic materials exhibiting spin-driven ferroelectricity offer diverse functionalities through magnetoelectric coupling. Electromagnons, spin excitations with electrical activity, are one such example. Resonantly enhanced non-reciprocal optical effects have been reported for electromagnons in the terahertz region. This presentation will outline the observation of nonlinear, nonreciprocal terahertz responses of electromagnons in multifunctional materials, specifically the bulk photovoltaic effect. It has been revealed that the terahertz photon is converted into dc current through the creation of electromagnon. This novel photovoltaic effect without photo-creation of charge carriers is explained by the extended shift current mechanism where the quantum geometric nature of electronics polarization plays the essential role. The observed terahertz functionality of multiferroics potentially enables the low-noise terahertz detection and terahertz energy conversion.
CK-6:L43 Effect of Superposition of Magnetic Field and High-frequency Electric Current on Magnetic and Electrical Properties of Composite Microwires
A. CHIZHIK, A. ZHUKOV, V. ZHUKOVA, University of Basque Country, San Sebastian, Spain
Relationship between magnetic and electrical properties of glass-coated microwires under high-frequency (HF) currents reveals a complex interplay between magnetization reversal and induced circular magnetic field. When electric current in MHz–GHz range flows through the microwire, the circular magnetic field strongly influences the surface magnetization. The mechanism of this reversal depends on the current amplitude, as the HF field induces helical states governed by amplitude and frequency. Kerr effect measurements demonstrate how HF currents alter hysteresis loop shapes, where sharp magnetization jumps replace gradual rotations. Interestingly, HF current effects contrast with tensile stress: while stress enhances circular magnetization, HF currents suppress it and modify the reversal mechanism. The strong dependence of circular coercivity on HF current parameters reflects dynamics of circular domain nucleation and propagation in outer shell, where current concentrates due to skin effect. At frequencies above 1 MHz, eddy currents damp domain-wall motion, making magnetic-moment rotation dominant mechanism behind magnetoimpedance. Thus, electrical excitation at HF fundamentally reshapes magnetic behavior, coupling magnetization processes with microwire’s electrical response.
CK-6:IL47 Optical Detection of Antiferromagnetic Order via Linear and Bilinear Magnetoelectric Effects
TSUYOSHI KIMURA, University of Tokyo, Tokyo, Japan
The Faraday effect and the magneto-optical Kerr effect observed in ferromagnetic materials are representative nonreciprocal optical effects, that is, optical responses which are different for counter-propagating light beams. Apart from such conventional effects, unconventional nonreciprocal optical effects occur in antiferromagnetic (AFM) materials showing linear or bilinear magnetoelectric (ME) effects. Examples of such optical effects include nonreciprocal directional dichroism (NDD) and nonreciprocal rotation of reflected light (NRR) in AFM materials showing the linear ME effect, and electric field-induced NDD in AFM materials showing the bilinear ME effect. In this presentation, we show experimental demonstrations of these nonreciprocal optical effects, which can be used to detect AFM order and distinguish domain states even in fully compensated AFM materials.
This work has been done in conjunction with K. Matsumoto, K. Kobayashi, M. Moromizato, K. Arakawa, T, Hayashida, and K. Kimura.
CK-6:L49 Innovative Approaches in Printed Magnetic Field Sensors: Flexibility, Sustainability, and Performance
S. MOSCH1, C. VOIGT1, M. VINNICHENKO1, D. MAKAROV2, 1Fraunhofer IKTS, Dresden, Germany; 2Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden, Germany
The manufacturing and application of printed magnetoresistive (MR) sensors has potential to revolutionize fields of wearable electronics, automotive engineering and others. This presentation provides a comprehensive overview of the development of anisotropic magnetoresistive (AMR) and large magnetoresistive (LMR) sensors, which are manufactured using screen printing on flexible substrates such as polymer films and ceramics. These printed sensors offer improved mechanical flexibility and the ability to produce large sensor arrays cost-effectively. AMR sensors, based on nickel-iron alloys, exhibit high sensitivity in the sub-mT range, while bismuth-based LMR sensors offer exceptional performance in higher magnetic fields above 100 mT. These conducting sensors change their electrical resistance when an external magnetic field is applied. The presentation highlights the entire process flow, including rapid laser sintering for densification of the printed structures, and introduces the essential parameters for manufacturing high-quality sensors. The applications of these sensors in position determination and human-machine interaction will be addressed as well. Initial demonstrators of flexible sensors with outstanding mechanical flexibility and large sensor arrays will be presented. The use of sustainable materials such as bismuth underscores the environmental friendliness of these technologies and demonstrates their potential for future industrial applications.