Quantum oscillations in Kondo insulator SmB6 has been observed for the first time by scientific workers from Prof. CHEN Xianhui’s group and his coworkers, which introduced torque magnetometry as an effective way of characterizing Kondo materials with 2D Fermi surfaces, and gave a better understanding of the nature of strong correlated heavy-fermion systems.
A topological insulator behaves as an insulator in its interior but contains a conducting surface. It is a triumph of single electron band theory in recent development of topological insulators.Kondo insulators, also known as Kondosemiconductor and heavy fermion semiconductors, are understood as materials with strongly correlated electrons. Kondo insulators can be used to explore whether similar exotic states of matter as in the topological insulators can rise in the presence of strong electronic interactions. Once the temperature is low enough, the electronic structure can be mapped to a state that resembles in a normal topological insulator, with a bulk insulating state and a conductive surface state.
Pioneering researchers have suggested the existence of the surface state of SmB6only in recent experiments. For the fist time, Prof. LI Lu’s group, researchers from Prof. CHEN Xianhui’s group and coworkers have observed the quantum oscillations in Kondo insulator SmB6 using torque magnetometry via the de Hass-van Alphen (dHvA) effect.
(A )The crystal structure of Kondo insulator SmB6; (B) Photograph of anSmB6single crystal.
With a single cubic crystal structure, SmB6 single crystals were grown by conventional flux methods. The anisotropy of the magnetic susceptibility can be measured directly by torque magnetometry.The observed oscillation patterns is shown to be two-dimensional(2D), revealing two Fermi surfaces on the (100) surface plane and one Fermi surface on the (101) surface plane. The measured Fermi surface cross sections scale as the inverse cosine function of the magnetic field tilt angles, which demonstrates the two-dimensional nature of the conducting electronic states of SmB6.
(A) and (B) Quantum oscillationpattern observed by torque magnetometry.
The work has been published in Science entitled “Two-dimensional Fermi surfaces in Kondo Insulator SmB6”. (Science 346, 1208 (2014) DOI: 10.1126/science.1250366)
(ZHAO Xuemei, USTC News Center)
