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1. Lithium and Vanadium Intercalation into Bilayer V ₂ Se ₂ O: Ferrimagnetic–Ferroelastic Multiferroics and Anomalous and Spin Transport

   https://doi.org/10.1002/advs.202512533  

   Zhang, Long; Liu, Yuxin; Ren, Junfeng; Ding, Guangqian; Wang, Xiaotian; Ni, Guangxin; Gao, Guoying; Cheng, Zhenxiang (January 2026, Advanced Science)

   Abstract Spin splitting in emerging altermagnets is nonrelativistic and momentum dependent, yet energy independent, and localized in momentum space, posing challenges for practical applications. Here, an intercalation‐driven paradigm is proposed for altermagnets to attain ameliorative electronic structures, multiferroic characteristics, and anomalous and spin transport functionalities. As a representative system, electrochemistry‐ and self‐intercalated V₂Se₂O bilayers are investigated, building on the recently reported room‐temperature K‐ and Rb‐intercalated V₂Se₂O family, utilizing density functional theory, Wannier function analyses, Monte Carlo simulations, and nonequilibrium Green's function methods. Intercalation induces room‐temperature intralayer ferrimagnetic and interlayer ferromagnetic orders (358 K for Li intercalation and 773 K for V intercalation), ferroelasticity (≈1% signal intensity), in‐plane uniaxial magnetic anisotropy, and metallization, while also modifying the anomalous Hall effect. Notably, Li‐ and V‐intercalated V₂Se₂O bilayers exhibit enhanced spin splitting and half‐metallic behavior, respectively, yielding near‐perfect spin filtering efficiency. Intercalation substantially enhances spin transport in V₂Se₂O‐based devices, enabling giant magnetoresistance (877%), ultrahigh thermal tunneling magnetoresistance (≈12 000%), and observable spin Seebeck and temperature negative differential resistance effects. This intercalation‐driven paradigm expands altermagnetic functionalities through multifunctional integration, offering promising avenues for advanced, miniaturized, room‐temperature exploitation of anomalous, electron, and spin transport properties. 

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2. Spontaneous anomalous Hall effect in two-dimensional altermagnets

   https://doi.org/10.1103/PhysRevB.111.184407  

   Sheoran, Sajjan; Dev, Pratibha (May 2025, Physical Review B)

   The anomalous Hall effect (AHE) is an efficient tool for detecting the Néel vector in collinear compensated magnets with spin-split bands, known as altermagnets (AMs). Here, we establish design principles for obtaining nonzero anomalous Hall conductivity in the recently proposed two-dimensional (2D) AMs using spin and magnetic group symmetry analysis. We show that only two of the seven nontrivial spin layer groups exhibit an unconventional in-plane AHE in which the Néel vector lies within the plane of the Hall current. Through first-principles simulations on bilayers of MnPSe3 and MnSe, we demonstrate the validity of our group theoretic framework for obtaining AHE with d- and i-wave altermagnetic orders, depending on the stacking of the bilayers. We find that the spin group symmetry is successful in determining the linear and cubic dependence of anomalous Hall conductivity in Néel vector space, although AHE is a relativistic effect. This work shows that the AHE in 2D AMs can probe the altermagnetic order and Néel vector reversal, thereby facilitating the miniaturization of altermagnetic spintronics. 

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3. Strain-tunable Berry curvature in quasi-two-dimensional chromium telluride

   https://doi.org/10.1038/s41467-023-38995-4  

   Chi, Hang; Ou, Yunbo; Eldred, Tim B.; Gao, Wenpei; Kwon, Sohee; Murray, Joseph; Dreyer, Michael; Butera, Robert E.; Foucher, Alexandre C.; Ambaye, Haile; et al (December 2023, Nature Communications)

   Abstract Magnetic transition metal chalcogenides form an emerging platform for exploring spin-orbit driven Berry phase phenomena owing to the nontrivial interplay between topology and magnetism. Here we show that the anomalous Hall effect in pristine Cr 2 Te 3 thin films manifests a unique temperature-dependent sign reversal at nonzero magnetization, resulting from the momentum-space Berry curvature as established by first-principles simulations. The sign change is strain tunable, enabled by the sharp and well-defined substrate/film interface in the quasi-two-dimensional Cr 2 Te 3 epitaxial films, revealed by scanning transmission electron microscopy and depth-sensitive polarized neutron reflectometry. This Berry phase effect further introduces hump-shaped Hall peaks in pristine Cr 2 Te 3 near the coercive field during the magnetization switching process, owing to the presence of strain-modulated magnetic layers/domains. The versatile interface tunability of Berry curvature in Cr 2 Te 3 thin films offers new opportunities for topological electronics. 

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4. Systemic consequences of disorder in magnetically self-organized topological MnBi ₂ Te ₄ /(Bi ₂ Te ₃ ) _n superlattices

   https://doi.org/10.1088/2053-1583/ac3cc6  

   Sitnicka, Joanna; Park, Kyungwha; Skupiński, Paweł; Grasza, Krzysztof; Reszka, Anna; Sobczak, Kamil; Borysiuk, Jolanta; Adamus, Zbigniew; Tokarczyk, Mateusz; Avdonin, Andrei; et al (December 2021, 2D Materials)

   Abstract MnBi 2 Te 4 /(Bi 2 Te 3 ) n materials system has recently generated strong interest as a natural platform for the realization of the quantum anomalous Hall (QAH) state. The system is magnetically much better ordered than substitutionally doped materials, however, the detrimental effects of certain disorders are becoming increasingly acknowledged. Here, from compiling structural, compositional, and magnetic metrics of disorder in ferromagnetic (FM) MnBi 2 Te 4 /(Bi 2 Te 3 ) n it is found that migration of Mn between MnBi 2 Te 4 septuple layers (SLs) and otherwise non-magnetic Bi 2 Te 3 quintuple layers (QLs) has systemic consequences—it induces FM coupling of Mn-depleted SLs with Mn-doped QLs, seen in ferromagnetic resonance as an acoustic and optical resonance mode of the two coupled spin subsystems. Even for a large SL separation ( n ≳ 4 QLs) the structure cannot be considered as a stack of uncoupled two-dimensional layers. Angle-resolved photoemission spectroscopy and density functional theory studies show that Mn disorder within an SL causes delocalization of electron wave functions and a change of the surface band structure as compared to the ideal MnBi 2 Te 4 /(Bi 2 Te 3 ) n . These findings highlight the critical importance of inter- and intra-SL disorder towards achieving new QAH platforms as well as exploring novel axion physics in intrinsic topological magnets. 

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5. Large anomalous Hall effect and negative magnetoresistance in half-topological semimetals

   https://doi.org/10.1038/s42005-023-01469-6  

   Zhu, Yanglin; Huang, Cheng-Yi; Wang, Yu; Graf, David; Lin, Hsin; Lee, Seng Huat; Singleton, John; Min, Lujin; Palmstrom, Johanna C.; Bansil, Arun; et al (December 2023, Communications Physics)

   Proposed mechanisms for large intrinsic anomalous Hall effect (AHE) in magnetic topological semimetals include diverging Berry curvatures of Weyl nodes, anticrossing nodal rings or points of non-trivial bands. Here we demonstrate that a half-topological semimetal (HTS) state near a topological critical point can provide an alternative mechanism for a large AHE via systematic studies on an antiferromagnetic (AFM) half-Heusler compound TbPdBi. We not only observe a large AHE with tanΘ^H≈ 2 in its field-driven ferromagnetic (FM) phase, but also find a distinct Hall resistivity peak in its canted AFM phase. Moreover, we observe a large negative magnetoresistance with a value of ~98%. Our in-depth theoretical modelling indicates that these exotic transport properties originate from the HTS state which exhibits Berry curvature cancellation between the trivial spin-up and nontrivial spin-down bands. Our study offers alternative strategies for improved materials design for spintronics and other applications. 

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