Physics

Room-temperature non-reciprocal Hall effect could heat up future technology development

The researchers deposited textured platinum nanoparticles, represented by red triangles, onto a silicon semiconductor, represented by blue squares. Electrons, represented by white circles and arrows, scatter asymmetrically from the nanoparticles, causing a voltage, represented by yellow arrows, flowing perpendicular to the current, represented by black arrows, applied to the semiconductor. The relationship between voltage and current can be described mathematically and is plotted as such on the right side of the image. Voltage is always proportional to the square of current. Credit: Mao Lab/Pennsylvania State University

An old physical phenomenon known as the Hall effect has revealed some new tricks, according to a team co-led by researchers from Pennsylvania State University and the Massachusetts Institute of Technology (MIT). They report their findings, which they say have potential implications for understanding the fundamental physics of quantum materials and developing applied technologies such as quantum communications and energy harvesting via radio frequencies in Nature Materials. .

The classical Hall effect occurs only in electrical conductors or semiconductors in the presence of a magnetic field. This is characterized by a newly formed voltage called the Hall voltage, which can be measured perpendicular to the current and is directly proportional to the applied current.

However, the newly discovered non-reciprocal Hall effect does not require a magnetic field. Discovered by a team led by Zhiqiang Mao, professor of physics, materials science and engineering, and chemistry at Penn State University, and Liang Fu, professor of physics at MIT, the effect is a function of the Hall voltage and applied current. Represented by relationships. This can be explained mathematically. Hall voltage is always proportional to the square of the current. The research team made their discovery in a microstructure consisting of textured platinum nanoparticles deposited on silicon.

Unlike the traditional Hall effect, which is driven by forces induced by magnetic fields, the non-reciprocal Hall effect occurs when conduction electrons, which are charge-carrying particles, interact with textured platinum nanoparticles. .

“In this study, we report the first observation of a giant non-reciprocal Hall effect at room temperature,” Mao said, noting that the pronounced geometrically asymmetric scattering of textured platinum nanoparticles made the observation possible. He explained that he did. “We also demonstrated the potential applications of this effect in broadband frequency mixing and wireless microwave detection. Masu.”

This research hinges on understanding how electrons scatter asymmetrically when interacting with asymmetric particles within the material. This process results in a violation of Ohm’s law, a fundamental tenet described by physicist Georg Ohm in 1827, which states that the current flowing through a conductor is proportional to the applied voltage. According to this law, in the absence of a magnetic field, the Hall voltage should be zero. However, the nonreciprocal Hall voltage that scales quadratically with electric current in textured platinum nanoparticles at zero magnetic field calls this principle into question, Mao said.

Mao said the discovery is even more interesting because studying such behavior typically requires low temperatures, below 280 degrees Fahrenheit. However, in this study, the asymmetric structure of the deposited platinum nanoparticles appears to generate a nonreciprocal Hall effect even at room temperature. This research could have applications in technologies such as quantum rectification and converting alternating current to direct current. And photodetection involves generating electrical signals from light, Mao said.

“This breakthrough advances our understanding of charge transport in materials,” said Mao, highlighting that asymmetric electron scattering is key to the existence of the non-reciprocal Hall effect in textured platinum nanoparticles. did. “This asymmetry reveals heterogeneous features in what should be a homogeneous landscape, and it is in these areas that we are most likely to discover new insights.”

Further information: Lujin Min et al., Giant room-temperature non-reciprocal Hall effect, Nature Materials (2024). DOI: 10.1038/s41563-024-02015-7

Provided by Pennsylvania State University

Citation: Room-temperature nonreciprocal Hall effect could heat up future technology development (October 24, 2024) https://phys.org/news/2024-10-room-temperature-nonreciprocal-hall- Retrieved October 24, 2024 from effect.html

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