Superconductivity in LaBi₃with AuCu₃-type structure

Abstract

We succeeded in synthesizing a new intermetallic compound with a AuCu3-type structure, LaBi3, by utilizing a high-pressure technique. Reacting Bi and LaBi at 450 °C under a pressure of 3.4 GPa resulted in the crystallization of LaBi3 with an a-axis lattice parameter of Sharp superconducting transitions were observed in both its magnetic susceptibility and electrical resistivity at 7.3–7.4 K. The upper critical field and Ginzburg–Landau coherence length ξ0 were estimated to be 1.70 T and 139 Å, respectively. The superconducting transition temperature Tc was found to decrease linearly with increasing applied pressure with a slope of −0.26 K GPa−1. Band structure calculations indicated that this compound has a multiband nature and that its Fermi energy is located exactly at one of the peak density of states.

Role of spin-orbit coupling in the physical properties of LaX3 ( X=In , P, Bi) superconductors

“…The calculated lattice constants for LaX 3 compare very well with previous experimental [30,31,43] and theoretical values [41,42]. In particular, the calculated lattice parameters for these intermetallic compounds with and without SOC are found to differ by less than 2% from their experimental values [30,31,43]. The presented values of bulk modulus for LaIn 3 and LaPb 3 materials are in gratifying agreement with previous LDA results [41], with a maximum difference of 5.0% for LaPb 3 .…”

“…2. In general agreement with previous works [41,43], the electronic [32] 194 Experimental [37] 170 FP-LAPW method within LDA [41] 2080 3720 2315 235 FP-LAPW method within GGA [42] 2316 4082 2573 140 structures of these superconductors reveal metallic character since at least one band crosses the Fermi level along all the considered symmetry directions. The inclusion of SOC causes some bands to split at the high-symmetry points in the Brillouin zone.…”

“…However, with inclusion of SOC, some phonon frequencies decrease in LaPb 3 and LaBi 3 , and their average electronphonon coupling parameters increase considerably, which causes enhancement in their T c values. Using the calculated value of the electron-phonon coupling parameter, the value of T c is estimated to be 0.69 K for LaIn 3 , 4.23 for LaPb 3 , and 6.88 K for LaBi 3 , which are consistent with the corresponding measured values of 0.70 K, 4.18 K, and 7.3 K [31,35,43]. Our results reveal that with phonon dispersions calculated with the inclusion of SOC, the superconductivity mechanism in these three superconductors can be explained very well with the traditional scheme involving electron-phonon interaction.…”

“…The calculated values for the equilibrium lattice parameter (a), the bulk modulus (B), and its pressure derivative (B ) with and without SOC are presented in Table I along with existing experimental [30,31,43] and theoretical [41,42] results. The calculated lattice constants for LaX 3 compare very well with previous experimental [30,31,43] and theoretical values [41,42]. In particular, the calculated lattice parameters for these intermetallic compounds with and without SOC are found to differ by less than 2% from their experimental values [30,31,43].…”

“…Very recently, using a high-pressure technique, Kinjo and co-workers [43] have researched for new compounds among the aforesaid LaX 3 compound and found that LaBi 3 also has the AuCu 3 -type structure with the T c value of 7.3 K, which is larger than the T c value for LaPb 3 . They proposed that the difference between the N(E F ) values for these two compounds is mainly responsible for their different T c values.…”