Tunnelling Spectroscopy on the Heavy-Fermion Superconductors UPd 2 Al 3 and UNi 2 Al 3 in the Normal State
- 20 April 1994
- journal article
- Published by IOP Publishing in Europhysics Letters
- Vol. 26 (3) , 203-208
- https://doi.org/10.1209/0295-5075/26/3/008
Abstract
Tunnelling measurements were performed on the new heavy-fermion superconductors UPd2Al3 (single crystal, Tc = 1.8 K) and UNi2Al3 (polycrystal, Tc = 1.2 K) and on the magnetic heavy-fermion superconductor URu2Si2 above and below the antiferromagnetic-ordering temperatures TN for T ≥ Tc. Tunnelling along the (a, b)-planes on UPd2Al3 shows that below TN ≈ 14 K an energy gap of about 13 meV is formed in the density of states. In contrast, no gap is found along the c-direction. For polycrystalline UNi2Al3 a gap of 10 meV is found below TN ≈ 4.8 K. Both the observed anisostropy and the values of the gaps of the new compounds prove surprisingly similar to URu2Si2. The values of the gaps appear to be set by crystal field excitation energies.Keywords
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