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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

Pressure induced evolution of superconducting transitions.(a) Temperature dependence of electrical resistivity for the LaRu2P2 single crystal in the temperature range 2 K to 300 K as measured under ambient pressure and 1.74 ± 0.05 GPa, shown by the black square and red circle symbols, respectively. The inset shows the temperature dependence of dc magnetic susceptibility of the sample as measured at an applied magnetic field of 20 Oe at ambient pressure. Both the magnetic susceptibility measured in zero-field-cooled (ZFC) and field-cooled (FC) modes are shown. (b) Temperature dependence of electrical resistivity for the LaRu2P2 single crystal under various pressures from ambient to 2.25 ± 0.05 GPa.
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f1: Pressure induced evolution of superconducting transitions.(a) Temperature dependence of electrical resistivity for the LaRu2P2 single crystal in the temperature range 2 K to 300 K as measured under ambient pressure and 1.74 ± 0.05 GPa, shown by the black square and red circle symbols, respectively. The inset shows the temperature dependence of dc magnetic susceptibility of the sample as measured at an applied magnetic field of 20 Oe at ambient pressure. Both the magnetic susceptibility measured in zero-field-cooled (ZFC) and field-cooled (FC) modes are shown. (b) Temperature dependence of electrical resistivity for the LaRu2P2 single crystal under various pressures from ambient to 2.25 ± 0.05 GPa.

Mentions: In Fig. 1a we show the temperature dependence of resistivity of the LaRu2P2 single crystal at ambient pressure and 1.74 GPa. Details about the growth and characterization of the crystal are given in Methods and Supplementary Information. It is clear that the residual resistivity ratio RRR = ρ(300 K)/ρ(5 K) = 27.0 is quite large, this indicates the cleanness of the crystal. The inset of Fig. 1a shows the magnetic susceptibility near the superconducting transition at a field of 20 Oe with the zero-field-cooled (ZFC) and field-cooled (FC) mode. Fig. 1b presents the temperature dependence of resistivity under different pressures from ambient to 2.25 GPa, one can see that the superconducting transition temperature Tc is clearly increased from 3.8 K to 5.8 K with the pressure increased to about 1.74 ± 0.05 GPa, then Tc drops down slightly with further increase of pressure. We can see a sudden broadening of resistive transition at 2.25 ± 0.05 GPa, this may arise from the possibility that the pressure transmitting to different parts inside the sample is inhomogeneous at that pressure, or due to some other unknown reasons. Here the Tc value was determined at the temperature with 50% of the normal state resistivity ρn. We should notice that, the Tc value determined by different methods may be slightly different. For example, the zero resistivity temperature Tc(zero) may roughly correspond to the onset transition point in the magnetic susceptibility measurements. That is why the Tc value determined in present paper is slightly higher than that determined in ref. 23. The enhancement ratio of Tc versus pressure, i.e. dTc/dp, is about 1.11 K/GPa. This value is quite big and very surprise to us, since it is comparable to that in some unconventional superconductors2122.


Pressure Induced Enhancement of Superconductivity in LaRu2P2.

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

Pressure induced evolution of superconducting transitions.(a) Temperature dependence of electrical resistivity for the LaRu2P2 single crystal in the temperature range 2 K to 300 K as measured under ambient pressure and 1.74 ± 0.05 GPa, shown by the black square and red circle symbols, respectively. The inset shows the temperature dependence of dc magnetic susceptibility of the sample as measured at an applied magnetic field of 20 Oe at ambient pressure. Both the magnetic susceptibility measured in zero-field-cooled (ZFC) and field-cooled (FC) modes are shown. (b) Temperature dependence of electrical resistivity for the LaRu2P2 single crystal under various pressures from ambient to 2.25 ± 0.05 GPa.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: Pressure induced evolution of superconducting transitions.(a) Temperature dependence of electrical resistivity for the LaRu2P2 single crystal in the temperature range 2 K to 300 K as measured under ambient pressure and 1.74 ± 0.05 GPa, shown by the black square and red circle symbols, respectively. The inset shows the temperature dependence of dc magnetic susceptibility of the sample as measured at an applied magnetic field of 20 Oe at ambient pressure. Both the magnetic susceptibility measured in zero-field-cooled (ZFC) and field-cooled (FC) modes are shown. (b) Temperature dependence of electrical resistivity for the LaRu2P2 single crystal under various pressures from ambient to 2.25 ± 0.05 GPa.
Mentions: In Fig. 1a we show the temperature dependence of resistivity of the LaRu2P2 single crystal at ambient pressure and 1.74 GPa. Details about the growth and characterization of the crystal are given in Methods and Supplementary Information. It is clear that the residual resistivity ratio RRR = ρ(300 K)/ρ(5 K) = 27.0 is quite large, this indicates the cleanness of the crystal. The inset of Fig. 1a shows the magnetic susceptibility near the superconducting transition at a field of 20 Oe with the zero-field-cooled (ZFC) and field-cooled (FC) mode. Fig. 1b presents the temperature dependence of resistivity under different pressures from ambient to 2.25 GPa, one can see that the superconducting transition temperature Tc is clearly increased from 3.8 K to 5.8 K with the pressure increased to about 1.74 ± 0.05 GPa, then Tc drops down slightly with further increase of pressure. We can see a sudden broadening of resistive transition at 2.25 ± 0.05 GPa, this may arise from the possibility that the pressure transmitting to different parts inside the sample is inhomogeneous at that pressure, or due to some other unknown reasons. Here the Tc value was determined at the temperature with 50% of the normal state resistivity ρn. We should notice that, the Tc value determined by different methods may be slightly different. For example, the zero resistivity temperature Tc(zero) may roughly correspond to the onset transition point in the magnetic susceptibility measurements. That is why the Tc value determined in present paper is slightly higher than that determined in ref. 23. The enhancement ratio of Tc versus pressure, i.e. dTc/dp, is about 1.11 K/GPa. This value is quite big and very surprise to us, since it is comparable to that in some unconventional superconductors2122.

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