Theoretical investigation of superconductivity in the non-centrosymmetric SrPtGe₃ and CaPtSi₃ compounds

Abstract

TITLETheoretical investigation of superconductivity in the non-centrosymmetric SrPtGe3 and CaPtSi3 compounds AUTHORS Uzunok, HY; Tütüncü, HM; Srivastava, GP; et al. JOURNAL Philosophical Magazine DEPOSITED IN OREWe present results for the structural, electronic, vibrational, and electron-phonon coupling properties of LaSn 3 and CaSn 3 adopting the simple cubic AuCu 3 -type structure obtained using the the generalized gradient approximation of the density functional theory and plane wave ab initio pseudopotential method. Our electronic results show that both materials display metallic character with several bands, which have mainly Sn 5p character, crossing the Fermi level. The calculated phonon spectrum of LaSn 3 accords very well with reported experimental measurements. The weights of the peaks in the Eliashberg spectral function of both compounds are enhanced with the use of experimental lattice constant in our electron-phonon calculation, increasing the value of average electron phonon coupling parameter from 0.876 to 0.937 for LaSn 3 (by 7%) and from 0.642 to 0.725 for CaSn 3 (by 13%). The use of experimental lattice constant also improves the agreement between theoretical and experimental values of the superconducting temperature for both compounds. IntroductionThe RX 3 (R = rare earth elements, X = In, Sn, Tl, Pb) intermetallic materials adopting the simple cubic AuCu 3 -type structure have received a large deal of attention from the scientific community because of their various properties changing from magnetism to superconductivity . Some of these compounds, such as PrSn 3 and NdSn 3 exhibit antiferromagnetic ordering with the Néel temperatures of 8.6 and 4.5 K [2, 10]. In addition, PrSn 3 and CePb 3 are also known as heavy-fermion compounds [15,23], while CeSn 3 has been classified as a dense Kondo compound displaying valence fluctuations [15,20]. Furthermore, the LaX 3 (X = In, Sn, Tl, Pb) compounds have received considerably more attention than other AuCu 3 -type compounds because they all display superconductivity. The superconducting transition temperature of LaSn 3 is reported to be around 6.5 K [1,6,27], which is relatively larger than the corresponding value for LaIn 3 , LaPb 3 and LaTl 3 [3,7,27,30]. The average electron-phonon coupling parameter of LaSn 3 has been reported to be 0.80 in the experimental work of Toxen and co-workers [5], which suggests that the electron-phonon interaction in this superconductor is of medium strength.The existence of superconductivity in LaSn 3 motivated several theoretical groups [31-35] to investigate its structural, elastic and electronic properties. Koelling [31] has been performed self-consistent linearized augmented plane wave (LAPW) calculations for the Fermi surface topology of LaSn 3 . The linearized muffin-tin-orbital method with the atomic sphere approximation (LMTO-ASA) [32] has been utilized to determine the electronic band structure of LaSn 3 . This theoretical [32] work suggests that LaSn 3 acts like a transition metal compound since the bonding sta...

High-Throughput Computational Screening and Design of CaPtAs-like Equiatomic Ternary Noncentrosymmetric Superconductors

“…In recent years, there has been a growing interest in noncentrosymmetric superconductors (NCSs), which can be defined as a type of superconductor that lacks an inversion center in the crystal structure. − One significant effect in NCSs is the antisymmetric spin–orbit coupling (ASOC), which allows for the mixed paring of spin-singlet and spin-triplet states under superconducting transition temperatures ( T c ), i.e., the (s + p)-wave paring. ,, These unconventional excitations make the existence of the Majorana zero modes or Majorana corner modes possible, which are treated as promising cornerstone that can be manipulated to realize the fault-tolerant topological quantum computations. − In addition, the presence of these mixed pairing can go beyond the conventional Bardeen–Cooper–Schrieffer (BCS) frame, displaying distinctive characteristics, which can lead to some fascinating properties such as nodal superconducting gaps , and anisotropic upper critical fields that surpass the Pauli limit …”