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In order to probe the changes in the valence state and magnetic properties of Eu metal under extreme pressure, x-ray absorption near-edge spectroscopy, x-ray magnetic circular dichroism and synchrotron Mossbauer spectroscopy experiments have been carried out. The Mossbauer isomer shift exhibits an anomalous pressure dependence, passing through a maximum near 20 GPa. Density functional theory has been applied to give insight into the pressure-induced changes in both Eus electronic structure and Mossbauer isomer shift. Contrary to previous reports, Eu is found to remain nearly divalent to the highest pressures reached (87 GPa) with magnetic order persisting to at least 50 GPa. These results should lead to a better understanding of the nature of the superconducting state found above 75 GPa and of the sequence of structural phase transitions observed to 92 GPa.
X-ray magnetic circular dichroism (XMCD) at the Eu L-edge (2p->5d) in two compounds exhibiting valence fluctuation, namely EuNi2(Si0.18Ge0.82)2 and EuNi2P2, has been investigated at pulsed high magnetic fields of up to 40 T. A distinct XMCD peak corr
The valence state of Yb ions in beta-YbAlB4 and its polymorph alpha-YbAlB4 has been investigated by using X-ray absorption and emission spectroscopy in SPring-8 at temperatures from 2 to 280 K. The observed Yb valence is 2.78 +- 0.01 in beta-YbAlB4 a
The pressure-dependent relation between Eu valence and lattice structure in model compound EuO is studied with synchrotron-based x-ray spectroscopic and diffraction techniques. Contrary to expectation, a 7% volume collapse at $approx$ 45 GPa is accom
We investigate LiVS2 and LiVSe2 with a triangular lattice as itinerant analogues of LiVO2, known for the formation of valence bond solid (VBS) state out of S = 1 frustrated magnet. LiVS2, which is located at the border between a metal and a correlate
The compound, Sr3NiPtO6, belonging to a K4CdCl6-type rhombohedral structure, has been reported not to exhibit magnetic ordering at least down to 1.8 K, despite a relatively large value of paramagnetic Curie temperature. This is attributable to geomet