Effect of magnetic order on the superfluid response of single-crystal ErNi${}_2$B${}_2$C: A penetration depth study

Abstract

We report measurements of the in-plane magnetic penetration depth $\Delta \lambda$(T) in single crystals of ErNi${}_2$B${}_2$C down to $\sim$0.1 K using a tunnel-diode based, self-inductive technique at 21 MHz. We observe four features: (1) a slight dip in $\Delta \lambda$(T) at the N$\acute{e}$el temperature $T_N$ = 6.0 K, (2) a peak at $T_{WFM}$ = 2.3 K, where a weak ferromagnetic component sets in, (3) another maximum at 0.45 K, and (4) a final broad drop down to 0.1 K. Converting to superfluid density ${\rho }_s$, we see that the antiferromagnetic order at 6 K only slightly depresses superconductivity. We seek to explain some of the above features in the context of antiferromagnetic superconductors, where competition between the antiferromagnetic molecular field and spin fluctuation scattering determines increased or decreased pairbreaking. Superfluid density data show only a slight decrease in pair density in the vicinity of the 2.3 K feature, thus supporting other evidences against bulk ferromagnetism in this temperature range.

arXiv comment15 pages, 5 figures

References in corpus (3)

• Nesting properties and anisotropy of the Fermi surface of LuNi${}_2$B${}_2$C
• Microwave Properties of Borocarbide Superconductors LnNi2B2C (Ln = Y, Er, Tm, Ho)
• Mean-field model of the ferromagnetic ordering in the superconducting phase of ErNi_2B_2C

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• Unconventional superconductivity and an ambient-pressure magnetic quantum critical point in single-crystal LaNiC${}_2$
• Bulk electronic structure of the antiferromagnetic superconducting phase in ErNi2B2C
• Observation of the spontaneous vortex phase in the weakly ferromagnetic superconductor ErNi${}_2$B${}_2$C: A penetration depth study
• Observation of anisotropic effect of antiferromagnetic ordering on the superconducting gap in ErNi2B2C