a research team from the graphene flagship at the university of manchester (u.k.) has reported on the first new type of quantum oscillation to be discovered in the past 30 years, which was created by applying a magnetic field to a heterostructure of graphene and boron nitride at high temperature.

the hofstadter butterfly phenomenon. (the university of manchester)

according to a report from the graphene flagship, quantum oscillations can be used by scientists to map the properties of new materials in proximity to a magnetic field and this research could lead to a host of different materials.

“the superlattice, created in graphene by its exact placement with regards to a periodically arranged boron nitride layer, interacts with the magnetic field in such a way that it is possible to tune its oscillation to manufacture bands and gaps in its electronics structure – meaning that the magnetic field can be used to tune the materials to be metallic, semiconducting or conducting,” the report explained.

it added, “this work also sheds further light on hofstadter’s butterfly, a fractal pattern that describes the behaviour of electrons in a magnetic field, measured experimentally for the first time in 2013 using a graphene and boron-nitride heterostructure…the research shown here illustrates how these complex fractal patterns can be viewed as langmuir quantization which is the quantization of cyclotron orbits (taking what is normally thought of as a circular orbit and instead viewing it as linear).”

the research was recently published in science. then abstract stated:

“cyclotron motion of charge carriers in metals and semiconductors leads to landau quantization and magneto-oscillatory behavior in their properties. cryogenic temperatures are usually required to observe these oscillations.

“we show that graphene superlattices support a different type of quantum oscillation that does not rely on landau quantization. the oscillations are extremely robust and persist well above room temperature in magnetic fields of only a few tesla.

“we attribute this phenomenon to repetitive changes in the electronic structure of superlattices such that charge carriers experience effectively no magnetic field at simple fractions of the flux quantum per superlattice unit cell. our work hints at unexplored physics in hofstadter butterfly systems at high temperatures.”