Superconductivity at 7.8 K in the ternary LaRu2As2 compound

Abstract

Here we report the discovery of superconductivity in the ternary LaRu 2 As 2 compound. The polycrystalline LaRu 2 As 2 samples were synthesized by the conventional solid state reaction method. Powder X-ray diffraction analysis indicates that LaRu 2 As 2 crystallizes in the ThCr 2 Si 2 -type crystal structure with the space group I4/mmm (No. 139), and the refined lattice parameters are a = 4.182(6) Å and c = 10.590(3) Å. The temperature dependent resistivity measurement shows a clear superconducting transition with the onset T c (critical temperature) at 7.8 K, and zero resistivity happens at 6.8 K. The upper critical field at zero temperature  0 H c2 (0) was estimated to be 1.6 T from the resistivity measurement. DC magnetic susceptibility measurement shows a bulk superconducting Meissner transition at 7.0 K, and the isothermal magnetization measurement indicates that LaRu 2 As 2 is a type-II superconductor.

Discovery of a novel 112-type iron-pnictide and La-doping induced superconductivity in Eu 1− x La x FeAs 2 ( x = 0–0.15)

“…Meanwhile, superconducting evidences around 100 K was reported in single unit cell film of FeSe on SrTiO 3 substrate [12]. Besides, some other layered transition metal pnictide superconductors were also discovered with much lower superconducting T c [13][14][15]. Therefore, it is still challenging to design and explore new iron-based superconductors with higher T c or novel structures for practical applications and physical research.…”

ThCr2Si2-type Ru-based superconductors LaRu2M2 (M = P and As): An ab-initio investigation

“…The ternary lanthanum ruthenium arsenide LaRu 2 As 2 with ThCr 2 Si 2 type structure is synthesized by Qi Guo et al [15]. He and his coworkers reported the bulk superconductivity in this compound with T c ~ 7.8 K. The magnetization measurements of LaRu 2 As 2 indicate that it is a bulk type-II superconductor [15].…”

Superconductivity in 122-Type Pnictides without Iron

“…ThCr 2 Si 2 -type structure has been found in SrNi 2 As 2 , LaRu 2 P 2 , and SrPd 2 As 2 , etc. [6,7,10,11,15,17,23,24,29] [18,19]. Structural phase transition is found in BaNi 2 As 2 from a high-temperature tetragonal phase to a low-temperature triclinic phase at T = 130 K [30].…”

“…Due to the apparent lack of magnetism, 122-IFPSs could provide perfect systems to study the interplay between structure and SC. In addition, proximity to a structural phase transition is not a prerequisite for SC for these compounds, as evidenced by the absence of a structural phase transition for some of them [6,7,9,11,12,14,15,17,[20][21][22][23][24][25]. LaRu 2 P 2 was found to be superconducting at about 4 K almost 30 years ago [6].…”

“…On the other hand, SC is also observed in other 122-type compounds formulated with AT 2 Pn 2 (A = alkaline-earth or rare-earth; T = transition metals; Pn = P, As or Sb) without iron [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. It has been reported that these 122-compounds show a variety of interesting phenomena, such as SC [1], heavy fermion [26], densed Kondo behavior [27], coexistence of SC and anti-ferromagnetism (AFM)/ferromagnetism (FM) /spin-density-wave (SDW) or charge density wave (CDW) [1,13,28].…”