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The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors.

Hinton JP, Thewalt E, Alpichshev Z, Mahmood F, Koralek JD, Chan MK, Veit MJ, Dorow CJ, Barišić N, Kemper AF, Bonn DA, Hardy WN, Liang R, Gedik N, Greven M, Lanzara A, Orenstein J - Sci Rep (2016)

Bottom Line: We find that τqp(T) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field.We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below.Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs.

View Article: PubMed Central - PubMed

Affiliation: Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

ABSTRACT
In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic "pseudogap" phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature Tc, suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τqp, as a function of temperature and magnetic field in underdoped HgBa2CuO(4+δ) (Hg-1201) and YBa2Cu3O(6+x) (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τqp(T) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs.

No MeSH data available.


Related in: MedlinePlus

Quasiparticle recombination lifetime.(a) Temperature dependence of τqp for a series of underdoped Hg-1201 samples. Curves are offset for clarity, as indicated in the figure. (b) Temperature dependence of the positive component of the transient reflectivity, ΔRQP and (c) the quasiparticle lifetime, τqp, for YBCO Ortho VIII with Tc = 67 K (black circles) and Hg-1201 with Tc = 71 K (blue squares). The temperature axis is normalized to Tc.
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f3: Quasiparticle recombination lifetime.(a) Temperature dependence of τqp for a series of underdoped Hg-1201 samples. Curves are offset for clarity, as indicated in the figure. (b) Temperature dependence of the positive component of the transient reflectivity, ΔRQP and (c) the quasiparticle lifetime, τqp, for YBCO Ortho VIII with Tc = 67 K (black circles) and Hg-1201 with Tc = 71 K (blue squares). The temperature axis is normalized to Tc.

Mentions: We turn now to measurements of the T dependence of the recombination lifetime of quasiparticles for T < Tonset. The decay curves in Fig. 1 were fit using a function of the form, , where the first term describes QP recombination, the second term accounts for finite risetime and the presence of a negative PG component, and the constant offset C captures a long-lived contribution that we attribute to local heating by the pump pulse (see Supplement for details on the fitting procedure). Figure 3a displays the evolution of τqp(T) with hole concentration in the Hg-1201 system. At each hole concentration we observe structure in the T-dependence of the quasiparticle recombination time at Tc. In underdoped samples there is a peak in τqp(T) at Tc that is most prominent in the Tc = 71 K sample and decreases in amplitude at lower and slightly higher hole concentration in a manner that appears to be correlated with the strength of the CDW.


The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors.

Hinton JP, Thewalt E, Alpichshev Z, Mahmood F, Koralek JD, Chan MK, Veit MJ, Dorow CJ, Barišić N, Kemper AF, Bonn DA, Hardy WN, Liang R, Gedik N, Greven M, Lanzara A, Orenstein J - Sci Rep (2016)

Quasiparticle recombination lifetime.(a) Temperature dependence of τqp for a series of underdoped Hg-1201 samples. Curves are offset for clarity, as indicated in the figure. (b) Temperature dependence of the positive component of the transient reflectivity, ΔRQP and (c) the quasiparticle lifetime, τqp, for YBCO Ortho VIII with Tc = 67 K (black circles) and Hg-1201 with Tc = 71 K (blue squares). The temperature axis is normalized to Tc.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829850&req=5

f3: Quasiparticle recombination lifetime.(a) Temperature dependence of τqp for a series of underdoped Hg-1201 samples. Curves are offset for clarity, as indicated in the figure. (b) Temperature dependence of the positive component of the transient reflectivity, ΔRQP and (c) the quasiparticle lifetime, τqp, for YBCO Ortho VIII with Tc = 67 K (black circles) and Hg-1201 with Tc = 71 K (blue squares). The temperature axis is normalized to Tc.
Mentions: We turn now to measurements of the T dependence of the recombination lifetime of quasiparticles for T < Tonset. The decay curves in Fig. 1 were fit using a function of the form, , where the first term describes QP recombination, the second term accounts for finite risetime and the presence of a negative PG component, and the constant offset C captures a long-lived contribution that we attribute to local heating by the pump pulse (see Supplement for details on the fitting procedure). Figure 3a displays the evolution of τqp(T) with hole concentration in the Hg-1201 system. At each hole concentration we observe structure in the T-dependence of the quasiparticle recombination time at Tc. In underdoped samples there is a peak in τqp(T) at Tc that is most prominent in the Tc = 71 K sample and decreases in amplitude at lower and slightly higher hole concentration in a manner that appears to be correlated with the strength of the CDW.

Bottom Line: We find that τqp(T) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field.We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below.Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs.

View Article: PubMed Central - PubMed

Affiliation: Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

ABSTRACT
In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic "pseudogap" phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature Tc, suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τqp, as a function of temperature and magnetic field in underdoped HgBa2CuO(4+δ) (Hg-1201) and YBa2Cu3O(6+x) (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τqp(T) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs.

No MeSH data available.


Related in: MedlinePlus