Anisotropic Fermi Surfaces, Electrical Transport, and Two-Dimensional Fermi Liquid Behavior in Layered Ternary Boride MoAlB

We report a study of fermiology, electrical anisotropy, and Fermi liquid properties in the layered ternary boride MoAlB, which could be peeled into two-dimensional (2D) metal borides (MBenes). By studying the quantum oscillations in comprehensive methods of magnetization, magnetothermoelectric power, and torque with the first-principle calculations, we reveal three types of bands in this system, including two 2D-like electronic bands and one complex three-dimensional-like hole band. Meanwhile, a large out-of-plane electrical anisotropy (\rho_bb/\rho_aa\sim 1100 and \rho_bb/\rho_cc\sim 500, at 2 K) was observed, which is similar to those of the typical anisotropic semimetals but lower than those of some semiconductors (up to 10^5). After calculating the Kadowaki–Woods ratio (\rm KWR = A/\gamma^2), we observed that the ratio of the in-plane A_a,c/\gamma^2 is closer to the universal trend, whereas the out-of-plane A_b/\gamma^2 severely deviates from the universality. This demonstrates a 2D Fermi liquid behavior. In addition, MoAlB cannot be unified using the modified KWR formula like other layered systems (Sr_2RuO_4 and MoOCl_2). This unique feature necessitates further exploration of the Fermi liquid property of this layered molybdenum compound.