Drastic Change of Electronic Properties in Ce₂MgSi₂ and CeNiIn₄ under High Pressure

Abstract

For an antiferromagnetic Ce 2 MgSi 2 single crystal sample, we measured the electrical resistivity under high pressure, and observed a remarkable phenomenon in the quantum critical region where the Néel temperature becomes zero. The corresponding critical pressure P c is 6 GPa. The electrical resistivity in the quantum critical region is found to increase steeply in magnitude with decreasing temperature, following the −log T dependence, and reaches a huge residual resistivity at low temperatures. Note that the corresponding resistivity is unchanged below about 1 K and does not decrease at lower temperatures. This behavior is very similar to the impurity Kondo effect, although Ce 2 MgSi 2 belongs to the Kondo lattice system. At pressures larger than P c 6 GPa in Ce 2 MgSi 2 , the residual resistivity becomes small, and the electronic state is changed into the so-called valence fluctuating system with a large Kondo temperature. The similar result is observed in another antiferromagnet CeNiIn 4 , revealing a huge residual resistivity and no decrease of the low-temperature resistivity at 16.2 and 18.1 GPa.

Machine Learning-Accelerated Discovery of A2BC2 Ternary Electrides with Diverse Anionic Electron Densities

“…Hence, they are not discussed in detail here. However, it is worth mentioning that the magnetic properties of Ce 2 MgSi 2 have already been studied in a previous work, 65 have been previously reported outside of the context of electrides, we believe this is the first report of La 2 YbGe 2 . We conducted Rietveld refinements of the X-ray diffraction pattern using the predicted structures of the three newly synthesized electrides.…”

“…Hence, they are not discussed in detail here. However, it is worth mentioning that the magnetic properties of Ce 2 MgSi 2 have already been studied in a previous work, but its electride nature had not been noticed.…”

“…The synthesis of Y 2 LiSi 2 was carried out following the method previously reported in the literature. 65 The three types of metals, Y, Li, and Si, were thoroughly mixed and annealed at 700 °C for 6 h in a stainless-steel crucible filled with argon (Ar) to produce the Y 2 LiSi 2 sample.…”

“…The obtained ingot was annealed at 1000 °C for 2 weeks for purification and then crushed and ground in an Ar-filled glovebox before use. The synthesis of Y 2 LiSi 2 was carried out following the method previously reported in the literature . The three types of metals, Y, Li, and Si, were thoroughly mixed and annealed at 700 °C for 6 h in a stainless-steel crucible filled with argon (Ar) to produce the Y 2 LiSi 2 sample.…”

Investigating the electronic states of UTe2 using X-ray spectroscopy

“…Not only magnetic and superconducting properties are strongly affected by pressure but the structure as well. Firstly, at the magnetic ordering critical pressure there is a volume reduction of about 3% 20 . At higher pressures, a structural transition to a body-centered tetragonal phase (I 4 /mmm) has been recently observed at 4-5 GPa 21,22 with an unexpected appearance of a new superconducting phase 21 .…”