Pressure effect on critical temperature for superconductivity and lattice parameters of AlB2-type ternary silicide YbGa1.1Si0.9

Ayako Ohmura; Koji Fujimaki; Fumihiro Ishikawa; Yuh Yamada; Naohito Tsujii; Motoharu Imai

doi:10.1103/PhysRevB.84.104520

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Pressure effect on critical temperature for superconductivity and lattice parameters of AlB2-type ternary silicide YbGa1.1Si0.9

Ayako Ohmura, Koji Fujimaki, Fumihiro Ishikawa, Yuh Yamada, Naohito Tsujii, Motoharu Imai

DOI 10.1103/PhysRevB.84.104520 · Physical Review B

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Abstract

Electrical resistivity and x-ray diffraction measurements have been carried out to investigate the pressure effect on the critical temperature for superconductivity (TC) and lattice parameters of AlB2-type superconducting silicide YbGa1.1Si0.9 (TC = 2.4 K) and its reference material CaGaSi (TC = 4.5 K). The electrical resistivity measurements up to 2.5 GPa reveal that TC decreases with pressure for both silicides and the pressure derivative of TC (dTC/dP) is −0.78 K/GPa and −0.026 K/GPa for YbGa1.1Si0.9 and CaGaSi, respectively. X-ray diffraction measurements up to 3.5 GPa indicate both silicides do not exhibit structural changes in this pressure range and they have similar values for the bulk moduli: B0=40±2 GPa for YbGa1.1Si0.9 and B0=42±1 GPa for CaGaSi. The relative pressure derivative of TC (dlnTC/dP) and logarithmic volume derivative of TC (dlnTC/dlnV) are −0.33 GPa−1 and 13 in YbGa1.1Si0.9. These values are about tenfold larger than those for other AlB2-type superconductors. Additionally, the origin of dlnTC/dP and dlnTC/dlnV in YbGa1.1Si0.9 relative to the pressure effect on the valence of Yb atoms is discussed.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
YbGa1.1Si0.9 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.4	Pressure unresolved	onset
YbGa1.1Si0.9 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.1	2.5 GPa	onset
CaGaSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	4.3	Pressure unresolved	onset
CaGaSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.9	2.4 GPa	onset
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39.6	Pressure unresolved	unknown
CaC6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	11.5	Pressure unresolved	unknown
YbC6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	6.5	Pressure unresolved	unknown
SrAlSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	4.9	Pressure unresolved	unknown