Isotope effect on the superfluid density in conventional and high-temperature superconductors
We investigate the isotope effect on the London penetration depth of a superconductor which measures nS/m* [n subscript s / m superscript asterisk], the ratio of superfluid density to effective mass. We use a simplified model of electrons weakly coupled to a single phonon frequency ωE [omega subscri...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Physical Society
2011
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| Online Access: | http://hdl.handle.net/1721.1/62554 https://orcid.org/0000-0001-7809-8157 |
| Summary: | We investigate the isotope effect on the London penetration depth of a superconductor which measures nS/m* [n subscript s / m superscript asterisk], the ratio of superfluid density to effective mass. We use a simplified model of electrons weakly coupled to a single phonon frequency ωE [omega subscript E], but assume that the energy gap Δ [delta] does not have any isotope effect. Nevertheless, we find an isotope effect for nS/m* [n subscript s / m superscript asterisk] which is significant if Δ [delta] is sufficiently large that it becomes comparable to ωE [omega subscript E], a regime of interest to high-Tc [high-T subscript c] cuprate superconductors and possibly other families of unconventional superconductors with relatively high Tc [T subscript c]. Our model is too simple to describe the cuprates and it gives the wrong sign of the isotope effect when compared with experiment, but it is a proof of principle that the isotope effect exists for nS/m* [n subscript s / m superscript asterisk] in materials where the pairing gap and Tc [T subscript c] are not of phonon origin and have no isotope effect. |
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