Effect of high pressure on charge density wave formation and magnetic structure in the cubic high-pressure phase of TbGe2.85

In this paper the charge density wave (CDW) and magnetic ordering for the high-pressure phase of ${\mathrm{TbGe}}_{2.85}$ with the ${\mathrm{AuCu}}_{3}$ structure have been studied by means of electrical resistivity and neutron powder diffraction at pressures up to 3 and 5 GPa, respectively. The electrical resistivity measurements showed that the charge density wave transition temperature ${T}_{\mathrm{CDW}}$ decreases with increasing the external pressure and the CDW transition in ${\mathrm{TbGe}}_{2.85}$ is suppressed at $P\ensuremath{\ge}2.6\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$. The N\'eel temperature ${T}_{N}$ is approximately independent of the pressure. The neutron powder diffraction at low temperatures and high pressures reveals the appearance of the second magnetic commensurate phase at $P=1.2\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$ with wave-vector $\mathbf{k}=(1/2,0,0)$. The calculation of the electronic structure of the ${\mathrm{TbGe}}_{3}$ (${\mathrm{AuCu}}_{3}$-type structure) compound was also performed. The high value of the electronic states at the Fermi level confirms the instabilities of the stoichiometric compound ${\mathrm{TbGe}}_{3}$.