A long-standing explanation for magnetoresistance may be incomplete. New evidence suggests a universal interfacial mechanism is at play.
A major advance in spintronics came with the discovery of unusual magnetoresistance (UMR). In this effect, the electrical resistance of a heavy metal changes when it is placed next to a magnetic insulator and the magnetization rotates within a plane that is perpendicular to the direction of the electric current.
This observation motivated the introduction of spin Hall magnetoresistance (SMR), a framework that quickly became widely accepted. SMR has since been used to explain UMR across many experimental settings, including standard magnetoresistance tests, spin-torque ferromagnetic resonance experiments, harmonic Hall voltage measurements, magnetic field sensors, and techniques for controlling magnetization or Néel-vector switching.
Over time, however, experiments revealed a broader and more puzzling picture. UMR was found to occur in many magnetic systems, even when no spin Hall material was present. Because the effect also appears in systems where SMR cannot apply (e.g., those without a spin Hall effect), researchers proposed a variety of alternative spin-current-related magnetoresistance (MR) models. These include Rashba-Edelstein MR, spin-orbit MR, anomalous Hall MR, orbital Hall MR, crystal-symmetry MR, orbital Rashba-Edelstein MR, and Hanle MR, all aimed at explaining the “SMR-like” signals seen in specific materials.
Experimental Evidence for a New Mechanism
More recently, Prof. Lijun Zhu from the Institute of Semiconductors, Chinese Academy of Sciences, working with Prof. Xiangrong Wang from the Chinese University of Hong Kong, reported clear experimental results pointing to a different origin of universal UMR. Their work shows that the effect arises from electron scattering at material interfaces, controlled by the magnetization and the interfacial electric field. This process is known as two-vector magnetoresistance and does not rely on spin currents.
Their experiments further reveal that extremely large UMR can appear even in single-layer magnetic metals. The measurements also show higher-order effects and follow a universal sum rule, all of which closely match the predictions of the two-vector MR model. Importantly, these results are obtained without the need to invoke spin-current-based mechanisms.
Reinterpreting Decades of Experimental Results
A systematic re-examination of existing literature further reveals that the most representative experimental data previously attributed to spin Hall magnetoresistance or other spin-current-related (or even unrelated) mechanisms can, in fact, be consistently explained within the framework of the two-vector MR theory. Moreover, they summarize a range of experimental and theoretical findings that strongly contradict spin-current-based MR models but are naturally accounted for by the two-vector MR mechanism.
These findings fundamentally challenge the long-standing and widely accepted SMR theory, offering the first robust experimental validation of the two-vector magnetoresistance model. By establishing a unified and universal physical origin for UMR, this work provides a simple yet comprehensive framework for understanding magnetoresistance phenomena in a broad range of spintronic systems.
Reference: “Physics origin of universal unusual magnetoresistance” by Lijun Zhu, Qianbiao Liu and Xiangrong Wang, 11 June 2025, National Science Review.
DOI: 10.1093/nsr/nwaf240
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A new experimental framework suggests that unusual magnetoresistance arises from interfacial electron scattering rather than spin currents, reshaping how magnetoresistance is understood across spintronic systems.
why?
Please ask the researchers to think deeply:
Why do electrons scatter?
The core of Topological Vortex Theory (TVT)—space is physical, and matter is its topological excitation—already provides a solid and elegant scientific path for understanding the origin of all things.
——Excerpted from https://t.pineal.cn/blogs/6255/A-Mathematical-and-Physical-Analysis-On-the-Origin-of-Objects.
When we pursue the ultimate truth of all things, the space in which our bodies and all things exist may itself be the final and deepest puzzle we need to explore. This is not only the pursuit of physics, but also the most magnificent exploration of the origin of the universe by human reason.
Based on the Topological Vortex Theory (TVT), space is an uniformly incompressible physical entity. Space-time vortices are the products of topological phase transitions of the tipping points in space, are the point defects in spacetime. Point defects do not only impact the thermodynamic properties, but are also central to kinetic processes. They create all things and shape the world through spin and self-organization.
In today’s physics, some so-called peer-reviewed journals—including Physical Review Letters, Nature, Science, and others—stubbornly insist on and promote the following:
1. Even though θ and τ particles exhibit differences in experiments, physics can claim they are the same particle. This is science.
2. Even though topological vortices and antivortices have identical structures and opposite rotational directions, physics can define their structures and directions as entirely different. This is science.
3. Even though two sets of cobalt-60 rotate in opposite directions and experiments reveal asymmetry, physics can still define them as mirror images of each other. This is science.
4. Even though vortex structures are ubiquitous—from cosmic accretion disks to particle spins—physics must insist that vortex structures do not exist and require verification. Only the particles that like God, Demonic, or Angelic are the most fundamental structures of the universe. This is science.
5. Even though everything occupies space and maintains its existence in time, physics must still debate and insist on whether space exists and whether time is a figment of the human mind. This is science.
6. Even though space, with its non-stick, incompressible, and isotropic characteristics, provides a solid foundation for the development of physics, physics must still insist that the ideal fluid properties of space do not exist. This is science.
and go on.
Is this the counterintuitive science they widely promote? Compromising with pseudo academic publications and peer review by pseudo scholars is an insult to science and public intelligence. Some so-called scholars no longer understand what shame is. The study of Topological Vortex Theory (TVT) reminds us that the most profound problems in physics often lie at the intersection of different theories. By exploring these border regions, we can not only resolve contradictions in existing theories but also discover new physical phenomena and application possibilities.
Under the topological vortex architecture, it is highly challenging for even two hydrogen atoms or two quarks to be perfectly symmetrical, let alone counter-rotating two sets of cobalt-60. Contemporary physics and so-called peer-reviewed publications (including Physical Review Letters, Science, Nature, etc.) stubbornly believe that two sets of counter rotating cobalt-60 are two mirror images of each other, constructing a more shocking pseudoscientific theoretical framework in the history of science than the “geocentric model”. This pseudo scientific framework and system have seriously hindered scientific progress and social development.
For nearly a century, physics has been manipulated by this pseudo scientific theoretical system and the interest groups behind it, wasting a lot of manpower, funds, and time. A large amount of pseudo scientific research has been conducted, and countless pseudo scientific papers have been published, causing serious negative impacts on scientific and social progress, as well as humanistic development.
Complexity does not necessarily mean that there is no logical and architectural framework to follow. Mathematics is the language and tool that reveals the motion of spacetime, rather than the motion itself. Although the physical form of spacetime vortices is extremely simple, their interaction patterns are highly complex, and we must develop more and richer mathematical languages to describe and understand them.
The development of the Topological Vortex Theory (TVT) reflects a progression from concrete physical phenomena to abstract mathematical modeling and, ultimately, to interdisciplinary unification. Its core innovation lies in forging the continuous spacetime geometry of general relativity with the discrete interactions of quantum field theory within the same topological dynamical system.
——Excerpted from https://scitechdaily.com/microscope-spacecrafts-most-precise-test-of-key-component-of-the-theory-of-general-relativity/#comment-909171.