Superconductivity in Mo5SiB2

Abstract

a b s t r a c tIn the Mo-Si binary system, Mo 5 Si 3 crystallizes in the W 5 Si 3 (T 1 phase) structure type. However, when boron replaces silicon in this compound, a structural transition occurs from the W 5 Si 3 prototype structure to the Cr 5 B 3 prototype structure (T 2 phase) at the composition Mo 5 SiB 2 . Mo 5 SiB 2 has received much attention in the literature as a candidate for structural application in high-temperature turbines, but its electronic and magnetic behavior has not been explored. In this work, we show that Mo 5 SiB 2 is a bulk superconducting material with critical temperature close to 5.8 K. The specific-heat, resistivity and magnetization measurements reveal that this material is a conventional type II BCS superconductor.

Superconductivity at 9 K inMo5PB2with evidence for multiple gaps

“…Further experimental analysis presented here will focus primarily on the Mo 5 P 1.1 B 1.9 sample. The T c values seen in these materials are the highest yet reported in this class of ternary superconductors, which include Mo 5 SiB 2 (T c = 5.8 K) [9], Nb 5 SiB 2 (T c = 7.2 K) [9], W 5 SiB 2 (T c = 5.8 K) [10], W 5−x Ta x SiB 2 (T c = 6.5 K) [25], and the closely related Nb 5 Si 2.4 B 0.6 (T c = 7.8 K) [22]. Figure 2 shows the results of magnetization measurements on Mo 5 P 1.1 B 1.9 .…”

“…The observation of superconductivity in several examples of Cr 5 B 3 -type compounds with the 512 stoichiometry suggests that further examination may produce more examples in this relatively new group of superconductors [9]. In the present work, we have studied the analogous Mo 5 PB 2 , and find that it too is a superconductor.…”

Intermetallic Cadmium Compounds M5T2Cd (M = Ca, Yb, Eu; T = Cu, Ag, Au) with Mo5B2Si-type Structure

“…Mo 5 B 2 Si has first been reported by Nowotny et al [3], and this compound attracted attention for high-temperature applications and its high oxidation resistance even at elevated temperatures. Superconductivity at 5.4 K was already reported in 1986 [4] and recently confirmed [5].…”

“…In contrast to the cadmium compounds discussed herein, the antimonides and bismutides RE 5 T 2 X (RE = rare earth element, T = Ni, Pd, Pt, Au; X = Sb, Bi) [6 -11] have only been obtained for the smaller trivalent rare earth elements. For one particular compound, Yb 5 Cu 2 Zn, we tested the cadmium-zinc substitution. Thus a whole family of ternary zinc compounds with the Mo 5 B 2 Si type is likely to exist.…”

“…Electronic structure calculation on Y 5 Ni 2 Sb [7] showed strong Y-Ni, Y-Sb, and Y-Y interactions which stabilize this rare earth-rich compound. Magnetic susceptibility data have so far only been reported for Er 5 In recent years we have shown that the indium atoms in diverse indides can partly or even completely be substituted by magnesium or cadmium [13, 14, and refs. therein].…”