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Pressure Induced Enhancement of Superconductivity in LaRu2P2.

Li B, Lu P, Liu J, Sun J, Li S, Zhu X, Wen HH - Sci Rep (2016)

Bottom Line: The ab-initio calculation shows that the superconductivity in LaRu2P2 at ambient pressure can be explained by the McMillan's theory with strong electron-phonon coupling.Detailed analysis of the pressure induced evolution of resistivity and upper critical field Hc2(T) reveals that the increase of Tc with pressure may be accompanied by the involvement of extra electron-boson interaction.This suggests that the Ru-based system has some commonality as the Fe-based superconductors.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.

ABSTRACT
To explore new superconductors beyond the copper-based and iron-based systems is very important. The Ru element locates just below the Fe in the periodic table and behaves like the Fe in many ways. One of the common thread to induce high temperature superconductivity is to introduce moderate correlation into the system. In this paper, we report the significant enhancement of superconducting transition temperature from 3.8 K to 5.8 K by using a pressure only of 1.74 ± 0.05 GPa in LaRu2P2 which has an iso-structure of the iron-based 122 superconductors. The ab-initio calculation shows that the superconductivity in LaRu2P2 at ambient pressure can be explained by the McMillan's theory with strong electron-phonon coupling. However, it is difficult to interpret the enhancement of Tc versus pressure within this picture. Detailed analysis of the pressure induced evolution of resistivity and upper critical field Hc2(T) reveals that the increase of Tc with pressure may be accompanied by the involvement of extra electron-boson interaction. This suggests that the Ru-based system has some commonality as the Fe-based superconductors.

No MeSH data available.


Related in: MedlinePlus

Resistive transitions and upper critical fields under ambient pressure and 1.94 GPa.(a,b) Temperature dependence of electrical resistivity for LaRu2P2 under various magnetic fields perpendicular to the basal plane at ambient pressure and 1.94 ± 0.05 GPa, respectively. (c) Temperature dependence of the upper critical field for the LaRu2P2 single crystal under ambient pressure and with a pressure of 1.94 ± 0.05 GPa, as shown by black squares and red circles, respectively. The transition temperature is obtained from Fig. 4a,b, using the 50%ρn criterion.
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f4: Resistive transitions and upper critical fields under ambient pressure and 1.94 GPa.(a,b) Temperature dependence of electrical resistivity for LaRu2P2 under various magnetic fields perpendicular to the basal plane at ambient pressure and 1.94 ± 0.05 GPa, respectively. (c) Temperature dependence of the upper critical field for the LaRu2P2 single crystal under ambient pressure and with a pressure of 1.94 ± 0.05 GPa, as shown by black squares and red circles, respectively. The transition temperature is obtained from Fig. 4a,b, using the 50%ρn criterion.

Mentions: In order to give support to the picture mentioned above, we measured the temperature dependence of the upper critical field of the sample under ambient and a pressure of 1.94 ± 0.05 GPa. In Fig. 4a,b, we show the resistive transitions of the sample under these two states at different magnetic fields. We determined Tc at different magnetic fields using the 50%ρn criterion and present the data in Fig. 4c. To determine Hc2(T), one usually should not use the criterion of zero resistance since otherwise the vortex motion will be involved. It is clear that not only the Tc value is increased, the slope −dHc2/dT changes from about 250 Oe/K at ambient pressure to about 600 Oe/K at 1.94 ± 0.05 GPa. According to the Ginzburg-Landau theory, near Tc it was estimated that28 (α = 0.5~1) with, the effective density of states (DOS) with the total electron-boson coupling constant λe−ph + λe−boson, where is the bare DOS at the Fermi energy. The increase of −dHc2/dT with pressure is very consistent with our previous conclusion that the enhancement of superconductivity is actually induced by the involvement of some extra electron-boson coupling which makes the system change from conventional electron-phonon dominated to moderate correlation governed Cooper pairing.


Pressure Induced Enhancement of Superconductivity in LaRu2P2.

Li B, Lu P, Liu J, Sun J, Li S, Zhu X, Wen HH - Sci Rep (2016)

Resistive transitions and upper critical fields under ambient pressure and 1.94 GPa.(a,b) Temperature dependence of electrical resistivity for LaRu2P2 under various magnetic fields perpendicular to the basal plane at ambient pressure and 1.94 ± 0.05 GPa, respectively. (c) Temperature dependence of the upper critical field for the LaRu2P2 single crystal under ambient pressure and with a pressure of 1.94 ± 0.05 GPa, as shown by black squares and red circles, respectively. The transition temperature is obtained from Fig. 4a,b, using the 50%ρn criterion.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834477&req=5

f4: Resistive transitions and upper critical fields under ambient pressure and 1.94 GPa.(a,b) Temperature dependence of electrical resistivity for LaRu2P2 under various magnetic fields perpendicular to the basal plane at ambient pressure and 1.94 ± 0.05 GPa, respectively. (c) Temperature dependence of the upper critical field for the LaRu2P2 single crystal under ambient pressure and with a pressure of 1.94 ± 0.05 GPa, as shown by black squares and red circles, respectively. The transition temperature is obtained from Fig. 4a,b, using the 50%ρn criterion.
Mentions: In order to give support to the picture mentioned above, we measured the temperature dependence of the upper critical field of the sample under ambient and a pressure of 1.94 ± 0.05 GPa. In Fig. 4a,b, we show the resistive transitions of the sample under these two states at different magnetic fields. We determined Tc at different magnetic fields using the 50%ρn criterion and present the data in Fig. 4c. To determine Hc2(T), one usually should not use the criterion of zero resistance since otherwise the vortex motion will be involved. It is clear that not only the Tc value is increased, the slope −dHc2/dT changes from about 250 Oe/K at ambient pressure to about 600 Oe/K at 1.94 ± 0.05 GPa. According to the Ginzburg-Landau theory, near Tc it was estimated that28 (α = 0.5~1) with, the effective density of states (DOS) with the total electron-boson coupling constant λe−ph + λe−boson, where is the bare DOS at the Fermi energy. The increase of −dHc2/dT with pressure is very consistent with our previous conclusion that the enhancement of superconductivity is actually induced by the involvement of some extra electron-boson coupling which makes the system change from conventional electron-phonon dominated to moderate correlation governed Cooper pairing.

Bottom Line: The ab-initio calculation shows that the superconductivity in LaRu2P2 at ambient pressure can be explained by the McMillan's theory with strong electron-phonon coupling.Detailed analysis of the pressure induced evolution of resistivity and upper critical field Hc2(T) reveals that the increase of Tc with pressure may be accompanied by the involvement of extra electron-boson interaction.This suggests that the Ru-based system has some commonality as the Fe-based superconductors.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.

ABSTRACT
To explore new superconductors beyond the copper-based and iron-based systems is very important. The Ru element locates just below the Fe in the periodic table and behaves like the Fe in many ways. One of the common thread to induce high temperature superconductivity is to introduce moderate correlation into the system. In this paper, we report the significant enhancement of superconducting transition temperature from 3.8 K to 5.8 K by using a pressure only of 1.74 ± 0.05 GPa in LaRu2P2 which has an iso-structure of the iron-based 122 superconductors. The ab-initio calculation shows that the superconductivity in LaRu2P2 at ambient pressure can be explained by the McMillan's theory with strong electron-phonon coupling. However, it is difficult to interpret the enhancement of Tc versus pressure within this picture. Detailed analysis of the pressure induced evolution of resistivity and upper critical field Hc2(T) reveals that the increase of Tc with pressure may be accompanied by the involvement of extra electron-boson interaction. This suggests that the Ru-based system has some commonality as the Fe-based superconductors.

No MeSH data available.


Related in: MedlinePlus