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Anisotropic Kondo Effect in Molybdenum/Carbon Nanotube Array Heterostructures
Zheng Wei1,2, Yu-Hao Wan3,4, Zhongpu Wang5
1Nanofabrication Laboratory, National Center for Nanoscience and Technology, Beijing100190, China.
ACS Applied Materials & Interfaces
|August 13, 2026
Summary
Researchers discovered an anisotropic Kondo effect in molybdenum/carbon nanotube heterostructures. This novel effect, driven by carbon p-electron magnetism, shows unique angular dependence and potential for spintronics.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- The Kondo effect, a phenomenon in dilute magnetic alloys, typically involves localized magnetic moments interacting with conduction electrons, leading to a resistivity minimum.
- Conventional understanding attributes the Kondo effect to s-d exchange interactions, but new systems may exhibit different mechanisms.
- Carbon nanotube (CNT) edges and transition metals like molybdenum offer novel platforms for exploring quantum phenomena.
Purpose of the Study:
- To investigate the Kondo effect in molybdenum/carbon nanotube array heterostructures.
- To explore the influence of interface structure and relative orientation on the Kondo response.
- To understand the origin of localized magnetic moments and their interaction with conduction electrons in this system.
Main Methods:
- Fabrication of molybdenum/carbon nanotube array heterostructures with partially unzipped CNT edges.
- Electrical transport measurements, including resistivity and magnetoresistance, as a function of temperature and magnetic field.
- Systematic variation of the relative orientation between the Mo current direction and the aligned CNT array.
Main Results:
- An anisotropic Kondo effect was observed, characterized by a resistivity minimum and logarithmic temperature dependence.
- Negative magnetoresistance (NMR) was observed when Mo strips were perpendicular to the CNT array, while positive magnetoresistance (PMR) emerged when parallel.
- The Kondo response exhibited a sin^2(alpha) angular dependence, indicating a strong directional coupling.
Conclusions:
- The study demonstrates an anisotropic Kondo effect originating from p electrons at unzipped CNT edges interacting with Mo conduction electrons.
- This effect is distinct from conventional s-d exchange Kondo effects and is explained by effective s-p exchange interactions.
- Findings highlight the potential of carbon-based materials for novel magnetism and spintronic applications.
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