Single crystal synchrotron x-ray diffraction study under pressure in UGe₂

Synchrotron radiation x-ray diffraction experiments on the pressure-induced ferromagnetic superconductor UGe₂ has been performed using a diamond anvil cell (DAC) diffractometer to study the correlation between the crystal structure and ferromagnetism. The oscillation photos covering the three-dimensional reciprocal spaces were taken both below and above a critical temperature T_x at pressures up to 1.1 GPa. Coupled charge density wave (CDW) and spin density wave (SDW) fluctuations were predicted as an origin of unusual properties of UGe₂ by Watanabe and Miyake, but no additional superlattice Bragg peaks corresponding to the CDW reflections could be observed, resulting in an upper limit of its intensity of ∼ 1 x 10∼4 to the fundamental Bragg peak intensity.