Fig. 1: Temperature dependence of in-plane λ relative to its value at the lowest temperature Δλ(T) for CeCoIn5, LaFePO, and KFe2As2. | Nature Communications

Fig. 1: Temperature dependence of in-plane λ relative to its value at the lowest temperature Δλ(T) for CeCoIn5, LaFePO, and KFe2As2.

From: Observation of the non-linear Meissner effect

Fig. 1

For each material, Δλ(T) is normalised by its value at T/Tc = 0.3. The data for CeCoIn5 and LaFePO have been shifted by ±0.15 along the λ axis for clarity. The inset shows the RF oscillator frequency change over the full temperature range to emphasise the superconducting transitions. Here Δf is measured relative to f(T) just above Tc and normalised to −1 at the lowest temperature. The mid-points of the transition are 2.1, 3.2 and 5.9 K for CeCoIn5, KFe2As2 and LaFePO respectively. For KFe2As2 and CeCoIn5 the RF field is parallel to the ab plane, and for LaFePO the RF field is parallel to the c-axis. Note that these transitions appear broader than the true distribution of Tc in the sample because of the strong T dependence of the normal state skin-depth and the finite sample thickness.

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