Superconductivity and Magnetic Order in a Strongly Interacting Fermi-System: URu2Si2

Single Crystal Growth of URu2Si2 by the Modified Bridgman Technique

“…Single-crystal X-ray diffraction measurements revealed the expected ThCr 2 Si 2 type structure with lattice constants a U = 4.133 (3) Å and c U = 9.58 (1) Å and a Th = 4.189 (2) Å and c Th = 9.745 (6) Å for URu 2 Si 2 and ThCr 2 Si 2 , respectively. These values are similar to those reported earlier [1][2][3][4]16,26]. For both materials, the direction perpendicular to the crystal surface is the c-axis, in agreement with earlier results from molten indium flux growth of URu 2 Si 2 ( Figure 1f) [16].…”

“…At the "hidden-order" temperature T 0 , χ(T) is abruptly reduced. All of these features are consistent with earlier results for poly-and single-crystal specimens [1][2][3][4]. Room temperature normalized electrical resistivity ρ 300K /ρ 0 vs. T measurements are shown in Figure 3 for three different batches of URu 2 Si 2 and a single batch of ThRu 2 Si 2 , where the only difference between these batches is the number of passes through the induction furnace hot zone ( Table 1).…”

“…χ(T) shows pronounced anisotropy where the c-axis is the easy axis, which is characteristic of the paramagnetism in URu 2 Si 2 [3,4]. The inverse magnetic susceptibility χ −1 reveals a Curie-Weiss temperature dependence χ(T) = C/(T−θ), and a fit to the data yields µ eff = 3.72 µ B and θ = −90.5 K. Near T coh,Ø ≈ 55 K, χ(T) evolves through a broad hump that may be associated with the onset of Kondo coherence [1][2][3][4]. At the "hidden-order" temperature T 0 , χ(T) is abruptly reduced.…”

“…Research into URu 2 Si 2 has been fueled by interest in an unusual amalgam of phenomena that are believed to originate from a blend of local and itinerant electron behavior, including a peculiar non-magnetic low temperature broken symmetry state ("hidden order"), for which the order parameter has yet to be identified [1][2][3][4]. The fact that it also hosts unconventional superconductivity makes this material even more attractive.…”

“…This is an important advance in crystal growth for these materials, because it provides an alternative way to produce single crystals that are needed for a variety of experiments: e.g., not only is it possible to cleave them, but their quality is also high enough to observe quantum oscillations, as seen in other specimens of similar quality [16,17]. Furthermore, previous studies of URu 2 Si 2 have benefitted from investigation of chemical substitution series [16,[18][19][20][21][22][23]. Most such work has focused on the substitution of elements with low vapor pressures that are easily dissolved in a stoichiometric melt.…”