Fabrication and magnetotransport properties of La-Ag-Ge thin films

Transition metal compounds with 4d and 5d orbitals can generate exotic electronic states and fascinating emergent phenomena due to their strong spin-orbit coupling. Here, we report the fabrication of three kinds of La-Ag-Ge compounds using molecular beam epitaxy. We have optimized growth conditions by systematically changing the Ag/La flux ratio while supplying same Ge and Ag flux. Hexagonal LaAgGe and tetragonal LaAg₂Ge₂ phases are stabilized under silver poor and rich conditions, respectively, while at intermediate Ag/La ratios we observe a phase-pure compound with (001) orientation. Notably, periodic peaks correspond to a d-spacing of 14.9 Å, which is not found in the ICSD powder diffraction database of the La–Ag–Ge system. Such a d-spacing matches those of the Ln₂AgGe₃ (Ln=Ce, Pr, Nd) family [1], suggesting the discovery of a novel compound.

Existing transport properties of La-Ag-Ge system are limited to LaAgGe bulk polycrystalline samples [2]. Our LaAgGe epitaxial films exhibits lower longitudinal resistivity than the bulk polycrystalline sample, enabling detailed magnetotransport measurements at low temperature. We will discuss magnetotransport properties of three La-Ag-Ge compounds and their electronic ground states.



[1] S. Sarkar et al., J. Solid State Chem. 229, 287-295 (2015).

[2] V. K. Pecharsky et al., J. Less-Common Metals 168, 257-267 (1991)