Charge density wave with anomalous temperature dependence in UPt2Si2

Abstract

Using single-crystal neutron and x-ray diffraction, we discovered a charge density wave (CDW) below 320 K, which accounts for the long-sought origin of the heat capacity and resistivity anomalies in UPt 2 Si 2. The modulation wave vector, Q mod , is intriguingly similar to the incommensurate wave vector of URu 2 Si 2. Q mod shows an unusual temperature dependence, shifting from commensurate to incommensurate position upon cooling and becoming locked at aproximately (0.42 0 0) near 180 K. Bulk measurements indicate a crossover toward a correlated coherent state around the same temperature, suggesting an interplay between the CDW and Kondo-lattice-like coherence before coexisting antiferromagnetic order sets in at T N = 35 K.

High temperature tetragonal crystal structure of UPt$_2$Si$_2$

“…However, details of this transition will be published elsewhere. [19] In order to verify the existence/non-existence of the (h 0 0): h = 2n + 1 type reflections at elevated temperatures, we have performed the experiment using the D9 instrument. During this experiment we have paid attention to the (h 0 0): h = 2n + 1 type reflections.…”

Electronic Tuning in URu2Si2 Through Ru to Pt Chemical Substitution

“…In order to probe the possibility that some nonisoelectronic substitution series share related phase diagrams, we investigated the chemical substitution series U(Ru 1−x Pt x ) 2 Si 2 . Here, Ru → Pt substitution is expected to be distinct from earlier electron doping series because 1) Ru is a 4d element while Pt is a 5d element, 2) Ru → Rh and Si → P are adjacent periodic table column substitutions while Ru → Pt is not, and 3) distinct bonding occurs for UPt 2 Si 2 (Ptasiewicz-Baķ et al, 1985;Lee et al, 2018;Lee et al, 2020), as evidenced by its formation in the CaBe 2 Ge 2 structure. These differences might be expected to drive the appearance of a distinct T-x phase diagram, as suggested by studies of other families of materials where transition metal → Pt substitution has been shown to be a versatile tuning parameter.…”

Electronic landscape of the f -electron intermetallics with the ThCr 2 Si 2 structure

“…A multitude of behaviors emerge from these simple crystal structures when f -elements are introduced into them, including local moment and complex magnetism ( 26 ), charge instabilities ( 27 ), structural instabilities ( 28 ), unconventional superconductivity ( 29 , 30 ), hidden order ( 1 ), multipolar order ( 31 ), and topologically protected electronic states ( 9 , 10 ). For the Ce-, Yb-, and U-based systems, the behavior is especially rich and is often understood in terms of the Ruderman-Kittel-Kasuya-Yosida (RKKY) and Kondo interactions ( 14 , 32 – 35 ), where (i) the RKKY interaction provides an indirect magnetic exchange between localized f-spins through the conduction electrons and favors magnetic ordering while (ii) the Kondo interaction drives hybridization between the conduction electron and f -states that results in screening of the f -spin and strongly reduces the effective magnetic moment.…”