Significantly Enhanced Lorenz Number in Twisted Bilayer Graphene

Twisted bilayer graphene (tblg) attracts significant interest in the scientific community due to its unique electronic properties, which arise from the Moiré pattern formed within it. Graphene is a well‐known material that violates the Wiedemann–Franz (WF) law at low temperatures. The Lorenz number ( L ) for tblg, twisted boron nitride, and their twisted heterostructure using the Boltzmann transport equation are theoretically calculated. The deviation from the WF law is highest for 21.8° tblg, with a maximum value of L = and = 73 at 40 K and carrier concentration. The peak value of 21.8° tblg is 1.6 times higher than that of graphene. The comparatively small deviation of the WF law for BN bilayer and graphene/BN heterostructures is observed at high temperatures. Our study suggests that the unique band feature of 21.8° tblg at the K ‐point enhances the electronic thermal conductivity, and a hump is observed at the carrier concentration of . Hence, an increase in the L is obtained in this carrier concentration.