Physicists discover new quantum effects in double-layer graphene

Theorists at the University of Texas at Dallas and colleagues in Germany first observed a rare phenomenon in a very simple material called the quantum anomalous Hall effect

Fan Zhang, associate professor in the School of Physics, Natural Sciences and Mathematics, is the author of this study published in the journal Nature on October 6.

The quantum Hall effect is a macroscopic phenomenon in which the lateral resistance in the material gradually changes in a quantized manner

"When the rare quantum anomalous Hall effect was studied before, the materials studied were complicated," Zhang said

Dr.

In a study published in 2011, theoretical physicist Zhang predicted that double-layer graphene will have five competing ground states, which are the material's temperature near absolute zero (minus 273.

"We predict that there will be five state groups in double-layer graphene, which compete with each other to become the ground state

In the experiment described in an article in the journal Nature, the researchers discovered eight different ground states in the fifth group, which simultaneously exhibited quantum anomalous Hall effect, ferromagnetism, and ferroelectricity

"We also proved that we can choose among the octet of the ground state by applying small external electric and magnetic fields and controlling the sign of the carrier," Weitz said

Although Zhang and Weitz stated that their main interest is to reveal the "beauty of basic physics," the ability to control the electronic properties of double-layer graphene to such a high degree may make it a potential candidate for future low-dissipation quantum information applications

"We predicted, observed, clarified and controlled a quantum anomalous Hall octabody, in which three compelling quantum phenomena-ferromagnetism, ferroelectricity, and zero-field quantum Hall effect-can coexist, even in double Cooperate with each other in layered graphene," Zhang said

Other authors of this article in the journal Nature include Xu Tianyi, a PhD student in physics at the University of Dallas, and researchers from Göttingen University and Ludwig Maximilian University in Munich

Zhang's research was funded by the Army Research Laboratory of the US Army Combat Capability Development Command and the National Science Foundation

Magazine

nature

DOI

10.

Methodological research

Experimental Study

Subject of research

not applicable

Article title

Quantum anomaly driven by orbital magnetism in double-layer graphene

Article publication date

6-October-2021