Good news! Amazing stuff! Mind boggling!
The MIT seems to be very busy in this research area, see also my previous blog post here from February.
"... The work, reported in the May 10 issue of Science, is one of several important discoveries by the same team over the past year involving a material that is a unique form of graphene. ...
The material behind this work, known as rhombohedral pentalayer graphene, was discovered two years ago ...
The material behind this work, known as rhombohedral pentalayer graphene, was discovered two years ago ...
In a ... paper last October, ... reported the discovery of three important properties arising from rhombohedral graphene. For example, they showed that it could be topological, or allow the unimpeded movement of electrons around the edge of the material but not through the middle. That resulted in a superhighway, but required the application of a large magnetic field some tens of thousands times stronger than the Earth’s magnetic field.
In the current work, the team reports creating the superhighway without any magnetic field. ...
In the current work, the team tinkered with the original system, adding a layer of tungsten disulfide (WS2). “The interaction between the WS2 and the pentalayer rhombohedral graphene resulted in this five-lane superhighway that operates at zero magnetic field,” . ...
Comparison to superconductivity
The phenomenon ... discovered in rhombohedral graphene that allows electrons to travel with no resistance at zero magnetic field is known as the quantum anomalous Hall effect. Most people are more familiar with superconductivity, a completely different phenomenon that does the same thing but happens in very different materials. ...
Similarly, the rhombohedral graphene superhighway currently operates at about 2 kelvins, or -456 degrees Fahrenheit. ..."
Similarly, the rhombohedral graphene superhighway currently operates at about 2 kelvins, or -456 degrees Fahrenheit. ..."
From the editor's summary and abstract:
"Editor’s summary
The quantum anomalous Hall effect has been observed in several materials, including those with a two-dimensional moiré structure. Han et al. observed this effect in a simpler two-dimensional material without a moiré potential: a five-layer rhombohedral graphene. The graphene was placed under a layer of tungsten disulfide, which induced spin-orbital coupling and was encapsulated by hexagonal boron nitride. The Hall resistance of the sample was fully quantized at zero magnetic field at a value corresponding to a high Chern number of 5. ...
Abstract
The quantum anomalous Hall effect (QAHE) is a robust topological phenomenon that features quantized Hall resistance at zero magnetic field. We report the QAHE in a rhombohedral pentalayer graphene-monolayer tungsten disulfide (WS2) heterostructure. Distinct from other experimentally confirmed QAHE systems, this system has neither magnetic element nor moiré superlattice effect. The QAH states emerge at charge neutrality and feature Chern numbers C = ±5 at temperatures of up to about 1.5 kelvin. This large QAHE arises from the synergy of the electron correlation in intrinsic flat bands of pentalayer graphene, the gate-tuning effect, and the proximity-induced Ising spin-orbit coupling. Our experiment demonstrates the potential of crystalline two-dimensional materials for intertwined electron correlation and band topology physics and may enable a route for engineering chiral Majorana edge states."
Large quantum anomalous Hall effect in spin-orbit proximitized rhombohedral graphene (no public access)
I retrieved the figure below from Google search results
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