Magnetic anisotropy and spin-glass behavior in single crystallineU2PdSi3

Abstract

We present the magnetic and transport properties of single crystallineU2PdSi3 measured with themagnetic field (H) (ormeasuring current, I) applied along two typical crystallographic directions, i.e. -axis and -axis (or -axis and -axis). For both directions, a spin-glass state is confirmed toform at low temperature with the same spin freezing temperatureTf (= 11.5 K), initialfrequency shift δTf (= 0.023)and activation energy Ea/kB (= 90.15 K) in zero dc field. Strong anisotropy in magnetic and transport behavior is found to be a significantfeature of U2PdSi3. The unusual ferromagnetic-like anomaly in ac susceptibility and dc magnetization curves aroundTm = 71 K is observed in the case of -axis but not in the cases of -axis. The characteristic temperatureTir, below which evident irreversible magnetism originated from random spin freezing can beobserved, shows much stronger field dependence for -axis than for -axis. Moreover, an unusual finding is that the electrical resistivity measurements indicatethe formation of magnetic Brillouin-zone boundary gaps and much larger magneticscattering for -axis, while the coherent-Kondo-effect-like behavior is obvious for -axis. We also emphasize that no resistivity minimum can be detected down to 2.5 K for eitherdirection. The observed magnetic and transport behaviors are compared with those in polycrystallineU2PdSi3 and other 2:1:3 intermetallic compounds.