Funded by the U.S. Department of Defense's Multidisciplinary University Research Program, researchers at Harvard University used two thin layers of MoSe2 separated by hexagonal boron nitride (hBN) to prepare a double-layer Vigna crystal that does not require a magnetic field or mor potential.
When the Coulomb interaction between electrons dominates its kinetic energy, it forms a Vigna crystal. Due to the complexity of the mechanism by which coulomb interactions govern kinetic energy, quantum melting of Vigna crystals produces singular intermediate phases and quantum magnetism. At present, the realization of quantum Wigner crystals requires the placement of semiconductor quantum traps in a strong magnetic field, and the strong magnetic field will inhibit the electron kinetic energy, which is not conducive to the interaction between the electron kinetic energy and the Coulomb interaction. To this end, the researchers prepared atomically thin transition metal disulfide heterostructures, in which a bilayer Vigna crystal was realized. This heterostructure consists of two MoSe2 monolayers separated by hBN. The carrier density in each MoSe2 layer can be controlled independently by the gate voltage of the top and bottom dielectric layers. Using this structure, two MoSe2 layers can be observed under low temperature conditions with stable associated insulating states under the doping of symmetrical (1:1) and asymmetrical (3:1, 4:1, 7:1) electrons. This is a double-layered Vigner crystal consisting of two interlocking triangular electronic lattices produced by interlayer interactions. This Vigna crystal can undergo quantum melting at an electron density of 6×1012 electrons/cm3 and a temperature of about 40 K.
This study produces Vigna crystals that do not require magnetic fields or mor potentials, which can be used for the study of multibody electronic states and magnetic quantum phase transitions.
论文：Bilayer Wigner crystals in a transition metal dichalcogenide heterostructure