Observation of Kondo cloud-coupling in a mirror-symmetric carbon nanotube array-molybdenum structure

Magnetic impurities in a non-magnetic metal are screened by conduction electrons, forming a spin cloud known as a Kondo cloud. Experimental detection of this Kondo screening cloud in dilute magnetic alloys remains challenging. Here we show evidence of Kondo clouds and their coupling in devices composed of mirror-symmetric carbon nanotube arrays separated by a molybdenum strip. The Kondo effect in these devices depends sensitively on the width of the molybdenum strip. For widths of 0.3-1.2 micrometers and 1.5-3.0 micrometers, the Kondo temperature forms two plateaus at about 107.8 kelvin and 15.8 kelvin, respectively. These results are explained by the formation of Kondo clouds and by intra-edge and inter-edge coupling within molybdenum. Calculations based on a two-spin model reproduce the two plateaus and their crossover. These findings may open opportunities for applications in spintronics and quantum computing. When magnetic impurities are present in a metal, conduction electrons form a spin cloud, also termed a Kondo cloud. Here, the authors provide evidence of Kondo clouds and their coupling in devices made up of mirror-symmetric carbon nanotube arrays separated with a molybdenum strip.