Novel Bulk\nQuantum Hall Effect in Nanostructured TaP\nMacroscopic Crystals

Bulk quantum Hall effect (QHE), the natural extension\nof the two-dimensional\n(2D) QHE, is one of the representative phenomena of coherent electron\ntransport. However, bulk QHE has rarely been reported in real materials\nwith macroscopic sizes. Here, we report a novel bulk QHE in macroscopic\nmillimeter-sized and nanostructured TaP crystals consisting of nanometer-scale\nlamellae. Specifically, the simultaneous quantum plateaus were observed\nin both transverse resistivity <i>ρ</i><sub><i>xy</i></sub> and vertical resistivity <i>ρ</i><sub><i>zz</i></sub>. The bulk QHE is attributable to synergetic\naction between Landau cyclotron movement under magnetic field <i>B</i> and periodically modulated potential due to the nanometer-scaled\nlamellae. This mechanism would form the fixed number of edge states\nalong <i>B</i>-perpendicular and <i>B</i>-parallel\ndirections respectively, equivalent to stacked 2D-QHE layers, leading\nto quantized <i>ρ</i><sub><i>xy</i></sub> and <i>ρ</i><sub><i>zz</i></sub>. Our\nwork verifies that microstructure engineering could result in the\ncoherent transport of electrons and generate new quantum phenomena\nin bulk materials.