Amazing stuff!
"Researchers found that when voltage was applied to a graphene stack, the layers slid into different arrangements and alternated between magnetic states."
"... researchers ... have found that electrically sliding the layers of ultrathin graphene can switch the material between distinct magnetic states that persist even after the voltage is removed. ...
“We discovered that if we focus on the much weaker bonds between the layers, known as van der Waals bonds, we were able to reconfigure the crystal structure,” Yasuda said. “Using voltage, we were able to shift alignment of the layers, something called ‘sliding,’ which changed how the graphene layers were stacked.”
The most stable and common pattern of these layers, or Bernal configuration, corresponded to a nonmagnetic state. Voltage transformed it into the less common and less stable pattern, rhombohedral configuration – a state associated with magnetism, superconductivity and exotic quantum phenomena. ..."
From the abstract:
"Layer stacking in two-dimensional materials can strongly impact electronic phases.
In graphene, for instance, the metastable rhombohedral stacking arrangement hosts correlated and topological electronic phases, which are absent in conventional Bernal stacking.
Here we use the sliding-induced first-order structural phase transition between Bernal and rhombohedral tetralayer graphene driven by gate voltages to manipulate the magnetic phase of the sample.
Through transport measurement on marginally twisted double-bilayer graphene samples, we observe bistable switching between a Bernal-dominant state and a rhombohedral–Bernal mixed state across a wide space of the gate-voltage phase diagram.
The structural phase transition induces a non-volatile switching between a non-magnetic and a ferromagnetic phase.
We characterize the latter phase via low-temperature electric transport measurements and observe an anomalous Hall effect.
The sign reversal of the anomalous Hall signal under opposite displacement fields suggests that the Hall signal may originate from domain boundaries between Bernal and rhombohedral regions.
Our experiments showcase how gating-induced sliding phase transitions of two-dimensional materials can provide on-demand toggle switching between complex phases and offer insights on the effect of stacking domain boundaries on the global response of the system."
Gate-induced layer sliding drives non-volatile switching of magnetism in tetralayer graphene (no public access)
Nonvolatile Switching of Magnetism via Gate-Induced Sliding in Tetralayer Graphene (preprint, open access)
Figure 1:Doping-induced sliding phase transition between rhombohedral and Bernal tetralayer graphene
Figure 2:Determination of switching boundary
No comments:
Post a Comment