VALENCE OF EU ION IN EU3IR4SN13 AT LOW-TEMPERATURES

To investigate the 4f magnetic state of Eu3Ir4Sn13, we have measured t he magnetization and specific-heat below the antiferromagnetic (AF) tr ansition temperature T-N = 10 K in the magnetic field along [100] and [110] axis. The magnetic entropy approaching Rln 8 indicates 2+ valenc e of Eu ion at low temperatures. The existence of antiferromagnetic sh ort-range interaction above T-N is inferred from suppressed magnetic e ntropy at T-N. The observed nuclear specific heat is mainly attributab le to Eu nucleus. The electronic specific heat coefficient gamma decre ases continuously with increasing held, while the magnetic specific he at is enhanced around the metamagnetic transition field of B-M = 2.8 T for B parallel to[100].