The central challenge addressed by the work is deeply rooted in magnetic symmetry. In an altermagnet, magnetic moments on different atomic sites can cancel in the conventional sense while still producing a momentum-dependent spin splitting in the electronic band structure. This unusual arrangement gives altermagnets characteristics that are distinct from both ordinary ferromagnets and conventional antiferromagnets. However, when the magnetic order points perpendicular to the material plane, the symmetry of the system can make it extremely difficult to read electrically. A conventional Hall signal, for example, is usually associated with a net magnetization, while an ideally compensated magnetic structure produces no obvious macroscopic magnetic moment. That limitation has hindered experiments designed to probe and control perpendicular altermagnetic states.

The new strategy relies on placing the altermagnet CrSb next to PtTe₂, a Dirac semimetal with unusual electronic properties. A Dirac semimetal is a material in which the energy bands can meet at special points or regions in momentum space, allowing charge carriers to behave in ways that resemble relativistic particles. These electronic states are highly sensitive to symmetry, interfaces and magnetic proximity effects. By growing PtTe₂ and CrSb together in an engineered heterostructure, the researchers created an interface where the electronic structure of the nonmagnetic or weakly magnetic component can be influenced by the altermagnetic order in CrSb. This interfacial coupling provides a route for converting an otherwise difficult-to-detect magnetic configuration into an electrical signal.

That conversion is described as an anomalous Hall read-out generated by the altermagnetic proximity effect. The anomalous Hall effect occurs when charge carriers traveling through a material are deflected sideways by mechanisms linked to broken time-reversal symmetry and spin–orbit coupling. In a conventional ferromagnet, the effect is often connected to the material’s magnetization. In the PtTe₂/CrSb system, however, the signal provides access to the magnetic order of CrSb even though the altermagnet is magnetically compensated. The proximity effect effectively transfers information about the Néel vector—the direction describing the arrangement of the opposing magnetic sublattices—into the electronic transport response of the adjacent Dirac semimetal. This gives researchers an electrical window into a magnetic state that is otherwise difficult to observe directly.

The distinction between magnetization and the Néel vector is essential for understanding why the advance matters. In a ferromagnet, switching the magnetization reverses a net magnetic moment, making the state relatively straightforward to detect with electrical, optical or magnetic probes. In an antiferromagnet or altermagnet, the relevant order parameter is instead the orientation of the sublattice moments. The Néel vector can change direction without producing a large overall magnetic field, which is attractive for dense device architectures because neighboring elements are less likely to disturb one another. At the same time, this compensation makes the order harder to manipulate and measure. The PtTe₂/CrSb interface addresses both sides of this problem by coupling the hidden magnetic orientation to charge transport and to current-induced torques.

The researchers also demonstrate electrical control through spin–orbit torque. When an electrical current flows through a material with strong spin–orbit coupling, the interaction between an electron’s motion and its spin can generate a nonequilibrium spin accumulation or spin current. When that spin angular momentum reaches a neighboring magnetic layer, it can exert a torque on the magnetic order. In the heterostructure, this mechanism provides an electrically generated force capable of manipulating the epitaxial perpendicular Néel vector in CrSb. The term “epitaxial” indicates that the layers are arranged with a defined crystallographic relationship, rather than being randomly oriented. Such structural order is important because altermagnetic properties depend strongly on crystal symmetry and on the precise direction of the magnetic axis.

Deterministic switching is particularly significant because it means the electrical stimulus can reliably select between distinct magnetic states rather than merely disturbing or randomly reorienting the order. For a memory device, a readable and repeatable switching pathway is indispensable. The combination reported here—an anomalous Hall signal for read-out and spin–orbit torque for writing—resembles the basic operating logic of modern magnetic memory, while using a compensated magnetic order parameter instead of a conventional ferromagnetic magnetization. If the approach can be integrated into scalable device geometries, it could offer a route toward memory elements that are compact, fast and resistant to unwanted magnetic cross-talk.

The PtTe₂/CrSb design also illustrates why heterostructures are becoming central to altermagnet research. A single material may possess remarkable magnetic symmetry but lack an efficient electrical interface for reading or switching it. Combining materials allows each layer to perform a different function: CrSb supplies the perpendicular altermagnetic order, while PtTe₂ contributes a Dirac electronic structure and strong spin–orbit physics that can translate electrical currents into magnetic control signals. The interface is therefore not merely a boundary between two crystals; it is an active functional region where magnetic symmetry, band structure and angular momentum transport become interconnected. This approach could be extended to other combinations of altermagnets, semimetals and spin–orbit materials.

The findings arrive as researchers worldwide search for alternatives to conventional magnetic memory and logic. Ferromagnetic devices are mature, but their stray fields, energy costs and scaling limits motivate the development of compensated magnetic systems. Altermagnets are especially appealing because they may combine the stability and low stray-field behavior associated with antiferromagnets with the spin-polarized transport phenomena more commonly associated with ferromagnets. The reported electrical reading and deterministic switching of perpendicular order directly confront two of the field’s most important practical barriers. Although further work will be needed to establish operating speeds, endurance, energy efficiency, thermal stability and fabrication compatibility, the PtTe₂/CrSb platform provides a concrete device-oriented framework for evaluating those questions.

More broadly, the study demonstrates how controlling symmetry can be just as important as selecting a magnetic material. The researchers did not simply seek a stronger magnetic signal; they engineered an interface that makes a symmetry-hidden order parameter visible and controllable through electricity. That conceptual shift could influence the design of future spintronic systems, in which information is encoded not only in magnetization but also in the orientation of compensated magnetic sublattices and in momentum-dependent spin textures. By showing that perpendicular altermagnetic order can be both detected and switched, the work expands the functional possibilities of altermagnetic heterostructures and brings the prospect of scalable altermagnetic memory closer to experimental reality.

Subject of Research: Electrical detection and deterministic switching of perpendicular altermagnetic order in a PtTe₂/CrSb heterostructure

Article Title: Electrical manipulation and detection of perpendicular altermagnetic order via a proximitized Dirac semimetal

Article References: Li, Z., He, W., Bai, H. et al. Electrical manipulation and detection of perpendicular altermagnetic order via a proximitized Dirac semimetal. Nat. Mater. (2026). https://doi.org/10.1038/s41563-026-02721-4

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41563-026-02721-4

Keywords: altermagnetism, spintronics, Dirac semimetal, PtTe₂, CrSb, anomalous Hall effect, spin–orbit torque, Néel vector, magnetic memory, magnetic heterostructures

The Hall effect, first discovered in 1879 by Edwin Hall, arises when an electric current passing through a conductor in a magnetic field experiences a transverse voltage due to the Lorentz force acting on moving charges. This fundamental phenomenon rapidly became a cornerstone in electromagnetism and solid-state physics, leading to various applied technologies and the discovery of novel quantum effects. Shortly after the initial identification of the classical Hall effect, physicists observed a similar but more enigmatic effect in ferromagnetic materials, which was designated the anomalous Hall effect. Unlike the classical Hall effect, where magnetic fields directly influence charge carriers, the AHE is intricately tied to the intrinsic magnetic properties of the material.

Despite being a subject of intense theoretical and experimental scrutiny for nearly a century, the exact origins of the anomalous Hall effect have remained elusive. Traditional understanding holds that the AHE stems primarily from spin-dependent scattering mechanisms and intrinsic spin-orbit coupling in ferromagnetic substances. However, sophisticated theoretical frameworks developed over the past few decades hinted that AHE-like behavior might also emerge in nonmagnetic materials under specific conditions. Such predictions, although tantalizing, lacked empirical verification until now.

The recent study, led by Associate Professor Masaki Uchida from the Institute of Science Tokyo, constitutes a significant leap forward by providing the first experimental evidence of AHE manifesting robustly in a nonmagnetic system. The results were published in the prestigious journal Physical Review Letters on September 2, 2025, marking a milestone in our understanding of electron transport phenomena in topological materials. This research not only validates prior theoretical predictions but also unlocks new avenues for electronic device engineering.

Central to the experiment is the choice of Cd₃As₂, a prototypical Dirac semimetal characterized by linear band crossings called Dirac points, where electrons mimic relativistic, massless particles. These materials harbor unique electronic topologies, making them fertile ground for observing exotic quantum phenomena. When subjected to an external perturbation, such as a magnetic field applied within the plane of the thin film, the inherent crystalline symmetries are broken, and the Dirac points split into pairs of Weyl nodes. This splitting fundamentally alters the Berry curvature distribution and electron dynamics, fostering conditions conducive to an anomalous Hall current.

Through meticulous band structure engineering, Uchida’s team adeptly suppressed contributions from the classical Hall effect, enabling the exclusive probing of the anomalous Hall conductivity. This delicate disentanglement relied on molecular beam epitaxy to fabricate atomically smooth Cd₃As₂ films with pristine symmetry properties. By finely tuning the magnetic field orientation and measuring the transverse voltage response, the team quantified the magnitude of the induced AHE with unprecedented precision, revealing a surprisingly large Hall angle comparable to ferromagnetic materials.

Crucially, further analysis of the experimental data illuminated that the dominant mechanism behind the observed AHE is not spin magnetization, as conventionally believed, but orbital magnetization—the magnetic moment arising from the cyclotron motion of electrons around the lattice sites. This insight introduces a paradigm shift in interpreting Hall effects, expanding the scope of orbital degrees of freedom in electronic transport. It underscores the role of Berry phase effects linked to the orbital motion of electrons, underscoring the richness of quantum geometrical contributions beyond spin physics.

The broader implications of this study are profound. By demonstrating that a giant anomalous Hall effect can exist in nonmagnetic materials, the findings greatly expand the landscape of materials suitable for spintronic and quantum electronic applications. Devices that exploit AHE to manipulate charge and magnetization could now be engineered without relying on ferromagnetic components, potentially enhancing energy efficiency, operational frequency, and stability under diverse conditions. This breakthrough sets the stage for innovative sensor technologies, memory storage, and information processing units that leverage orbital-controlled phenomena.

Moreover, the experimental approach pioneered by Uchida’s group—combining precision thin-film growth with directional magnetic field application and transport measurements—provides a versatile platform to probe subtle electron correlations and topological states in a variety of materials. The universal applicability of this methodology paves the way for exploring uncharted territories, such as novel topological phases and emergent quantum states governed by orbital magnetism, which have remained experimentally inaccessible until now.

The discovery also invites renewed theoretical investigations aimed at comprehensively modeling the interplay between orbital magnetization, Berry curvature, and electronic band structure under symmetry-breaking perturbations. It challenges conventional spin-based narratives in magnetotransport and compels physicists to revisit foundational models of the Hall effect with an expanded conceptual toolkit. This evolving understanding may influence future quantum material design, prioritizing orbital characteristics as key tunable parameters.

In conclusion, this study not only answers a long-standing question in condensed matter physics but also serves as a catalyst for interdisciplinary advances at the nexus of materials science, electronics, and quantum physics. As Associate Professor Uchida remarks, the demonstration of AHE in nonmagnetic Dirac semimetals reshapes our understanding and promises technological innovations that harness the orbital dynamics of electrons. With further research and development, this phenomenon could usher in a new generation of electronic devices exhibiting remarkable functionalities.

The Institute of Science Tokyo, formed in 2024 through the pioneering merger of Tokyo Medical and Dental University with Tokyo Institute of Technology, represents a vibrant hub for cutting-edge scientific research and technological innovation. This discovery distinctly exemplifies their mission of advancing human wellbeing through transformative science. Supported by notable organizations including the Japan Science and Technology Agency and the Ministry of Education, Culture, Sports, Science and Technology, the team’s achievements spotlight Japan’s prominent role in next-generation condensed matter physics.

As the implications of this research reverberate through the physics community and beyond, the anomalous Hall effect in nonmagnetic Dirac semimetals heralds a new chapter characterized by exciting possibilities and fundamental insights into the quantum properties of matter.

Subject of Research:

Article Title: Anomalous Hall effect in the Dirac semimetal Cd3As2 probed by in-plane magnetic field

News Publication Date: 2-Sep-2025

Web References:

• https://journals.aps.org/prl/accepted/10.1103/5d7l-mr7k

References:

• Physical Review Letters, “Anomalous Hall effect in the Dirac semimetal Cd3As2 probed by in-plane magnetic field,” 2025. DOI: 10.1103/5d7l-mr7k

Image Credits: Institute of Science Tokyo

Keywords

Physical sciences, Applied sciences and engineering, Electrical engineering, Electronics, Electronic devices