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Pressure-induced electronic phase separation of magnetism and superconductivity in CrAs.

Khasanov R, Guguchia Z, Eremin I, Luetkens H, Amato A, Biswas PK, Rüegg C, Susner MA, Sefat AS, Zhigadlo ND, Morenzoni E - Sci Rep (2015)

Bottom Line: The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar.At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreases upon increasing the pressure.Our results indicate that the less conductive magnetic phase provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs).

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.

ABSTRACT
The recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreases upon increasing the pressure. In the intermediate pressure region (3.5 < or ~  p < or ~ 7 kbar) the superconducting and the magnetic volume fractions are spatially phase separated and compete for phase volume. Our results indicate that the less conductive magnetic phase provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs). A scaling of ρs with Tc(3.2) as well as the phase separation between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs.

No MeSH data available.


Related in: MedlinePlus

Correlation between Tc and λ−2(0).Superconducting critical temperature Tc versus inverse squared zero-temperature magnetic penetration depth λ−2(0) of CrAs. The red line is  fit to CrAs data with the exponent n = 3.2(2). The black, green and blue lines are empirical relations for some phonon mediated BCS superconductors (n = 3.1, Ref. 28), cuprate and Fe-Based high-temperature superconductors (n = 1, Refs 21, 22, 23, 24, 25, 26) and molecular superconductors (n = 2/3, Ref. 27), respectively.
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f4: Correlation between Tc and λ−2(0).Superconducting critical temperature Tc versus inverse squared zero-temperature magnetic penetration depth λ−2(0) of CrAs. The red line is fit to CrAs data with the exponent n = 3.2(2). The black, green and blue lines are empirical relations for some phonon mediated BCS superconductors (n = 3.1, Ref. 28), cuprate and Fe-Based high-temperature superconductors (n = 1, Refs 21, 22, 23, 24, 25, 26) and molecular superconductors (n = 2/3, Ref. 27), respectively.

Mentions: Figure 3c,d show that Tc and λ−2(0) have similar pressure dependences, which could point to a possible correlation between these quantities. The famous “Uemura line” establishes a linear relation between Tc and λ−2(0) for various families of underdoped cuprate high-temperature superconductors2122. A similar linear relation was observed in recently discovered Fe-based superconductors23242526. In molecular superconductors λ−2(0) was found to be proportional to  27, while in some phonon mediated BCS superconductors 28. Figure 4 shows that in CrAs λ−2(0) the data scales as thus suggesting that superconductivity in CrAs is most probably BCS like and is mediated by phonons.


Pressure-induced electronic phase separation of magnetism and superconductivity in CrAs.

Khasanov R, Guguchia Z, Eremin I, Luetkens H, Amato A, Biswas PK, Rüegg C, Susner MA, Sefat AS, Zhigadlo ND, Morenzoni E - Sci Rep (2015)

Correlation between Tc and λ−2(0).Superconducting critical temperature Tc versus inverse squared zero-temperature magnetic penetration depth λ−2(0) of CrAs. The red line is  fit to CrAs data with the exponent n = 3.2(2). The black, green and blue lines are empirical relations for some phonon mediated BCS superconductors (n = 3.1, Ref. 28), cuprate and Fe-Based high-temperature superconductors (n = 1, Refs 21, 22, 23, 24, 25, 26) and molecular superconductors (n = 2/3, Ref. 27), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561900&req=5

f4: Correlation between Tc and λ−2(0).Superconducting critical temperature Tc versus inverse squared zero-temperature magnetic penetration depth λ−2(0) of CrAs. The red line is fit to CrAs data with the exponent n = 3.2(2). The black, green and blue lines are empirical relations for some phonon mediated BCS superconductors (n = 3.1, Ref. 28), cuprate and Fe-Based high-temperature superconductors (n = 1, Refs 21, 22, 23, 24, 25, 26) and molecular superconductors (n = 2/3, Ref. 27), respectively.
Mentions: Figure 3c,d show that Tc and λ−2(0) have similar pressure dependences, which could point to a possible correlation between these quantities. The famous “Uemura line” establishes a linear relation between Tc and λ−2(0) for various families of underdoped cuprate high-temperature superconductors2122. A similar linear relation was observed in recently discovered Fe-based superconductors23242526. In molecular superconductors λ−2(0) was found to be proportional to  27, while in some phonon mediated BCS superconductors 28. Figure 4 shows that in CrAs λ−2(0) the data scales as thus suggesting that superconductivity in CrAs is most probably BCS like and is mediated by phonons.

Bottom Line: The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar.At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreases upon increasing the pressure.Our results indicate that the less conductive magnetic phase provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs).

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.

ABSTRACT
The recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreases upon increasing the pressure. In the intermediate pressure region (3.5 < or ~  p < or ~ 7 kbar) the superconducting and the magnetic volume fractions are spatially phase separated and compete for phase volume. Our results indicate that the less conductive magnetic phase provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs). A scaling of ρs with Tc(3.2) as well as the phase separation between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs.

No MeSH data available.


Related in: MedlinePlus