High-pressure single-crystal synchrotron diffraction study of MnGe and related compounds

Single crystal synchrotron diffraction for pressures up to 50 GPa has revealed an essential difference in structural properties and compressibility of MnGe compared with Mn_1−x Co_x Ge and Mn_1−x Fe_x Ge solid solutions. A negative thermal expansion has been observed for MnGe at low-temperatures and high-pressures. The single crystal refinement has shown a discontinuous change of the atomic coordinates and Mn–Ge interatomic distances of MnGe in contrast to Mn_0.1Co_0.9Ge. These peculiarities of MnGe are likely to be associated with high-spin–low-spin transition. The relation between anisotropy of the coordination of Mn-atom and its magnetic moment is discussed. (paper)