First observation of superconductivity in LaCu₆ and possible applications

We have measured the ac susceptibility and resistivity of highly pure samples of the intermetallic compound LaCu₆ down to ultralow temperatures. We have prepared the samples by arc melting of stoichiometric amounts of 99.99\% La and 99.9999\% Cu in a water-cooled copper crucible under Ar protective atmosphere and analysed them by x-ray diffraction and SQUID magnetometry. At T≤T_c = 0.16 K we observe a superconducting transition. Due to the manifold physical properties of isostructural ReCu₆ compounds (e.g. RE = Ce: heavy fermion system, RE = Pr: hyperfine enhanced nuclear spin system, RE = Nd: electronic antiferromagnet), numerous studies of interplay phenomena may become possible in the quasibinary compounds RE_1-xLa_xCu₆, respectively.