Observation of a crossover from nodal to gapped superconductivity in Lu&lt;em&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/em&gt;Zr&lt;sub&gt;1-&lt;em&gt;x&lt;/em&gt;&lt;/sub&gt;B&lt;sub&gt;12&lt;/sub&gt;

Kirschner, Franziska K.K.; Sluchanko, Nikolay E.; Filipov, Vladimir B.; Pratt, Francis L.; Baines, Chris; Shitsevalova, Natalya Yu.; Blundell, Stephen J.

doi:10.1103/PhysRevB.98.094505

Observation of a crossover from nodal to gapped superconductivity in Lu_xZr_1-xB₁₂

Kirschner FKK, Sluchanko NE, Filipov VB, Pratt FL, Baines C, Shitsevalova NY & Blundell SJ

Citation

Kirschner, F. K. K., Sluchanko, N. E., Filipov, V. B., Pratt, F. L., Baines, C., Shitsevalova, N. Y., & Blundell, S. J. (2018). Observation of a crossover from nodal to gapped superconductivity in Lu_xZr_1-xB₁₂. Physical Review B, 98(9), 094505 (6 pp.). https://doi.org/10.1103/PhysRevB.98.094505

Persistent URL https://www.dora.lib4ri.ch/psi/islandora/object/psi:5569

We have determined the superconducting and magnetic properties of four samples of Lu_xZr_1-xB₁₂ (x = 0.04, 0.07, 0.17, and 0.8) using muon spin rotation (μSR) and magnetometry measurements. We observed a strong magnetic signal in both the μSR and magnetometry data in one sample (x = 0.07), likely caused by the formation of static moments of size ≈1 μ_B due to a clustering effect of the Lu³⁺ ions. In all other samples, we find only a small magnetic signal in the μSR data thought to originate from boron nuclei in the B₁₂ cages. The superconductivity is found to evolve with x, with a decrease in x resulting in an increase in critical temperature and a decrease of the penetration depth. Most remarkably, we find evidence for the formation of nodes in the superconducting gap for x ≤ 0.17, providing a potential new example of an s-to-s + d-wave crossover in a superconductor.