%0 Journal Article %T Magnetic anisotropy, unusual hysteresis and putative "up-up-down" magnetic structure in EuTAl4Si2 (T = Rh and Ir) %+ Department of Condensed Matter Physics and Materials Science [TIFR] (CMPMS) %+ Service de physique de l'état condensé (SPEC - UMR3680) %A Maurya, Arvind %A Thamizhavel, A. %A Dhar, S.K. %A Bonville, Pierre %< avec comité de lecture %@ 2045-2322 %J Scientific Reports %I Nature Publishing Group %8 2015 %D 2015 %R 10.1038/srep12021 %Z Physics [physics]Journal articles %X We present detailed investigations on single crystals of quaternary EuRhAl4Si2 and EuIrAl4Si2. The two compounds order antiferromagnetically at TN1 = 11.7 and 14.7 K, respectively, each undergoing two magnetic transitions. The magnetic properties in the ordered state present a large anisotropy despite Eu2+being an S-state ion for which the single-ion anisotropy is expected to be weak. Two features in the magnetization measured along the c-axis are prominent. At 1.8 K, a ferromagnetic-like jump occurs at very low field to a value one third of the saturation magnetization (1/3 M0) followed by a wide plateau up to 2 T for Rh and 4 T for Ir-compound. At this field value, a sharp hysteretic spin-flop transition occurs to a fully saturated state (M0). Surprisingly, the magnetization does not return to origin when the field is reduced to zero in the return cycle, as expected in an antiferromagnet. Instead, a remnant magnetization 1/3 M0 is observed and the magnetic loop around the origin shows hysteresis. This suggests that the zero field magnetic structure has a ferromagnetic component, and we present a model with up to third neighbor exchange and dipolar interaction which reproduces the magnetization curves and hints to an “up-up-down” magnetic structure in zero field. %G English %2 https://cea.hal.science/cea-01365544/document %2 https://cea.hal.science/cea-01365544/file/srep12021.pdf %L cea-01365544 %U https://cea.hal.science/cea-01365544 %~ CEA %~ CNRS %~ IRAMIS-SPEC %~ CEA-UPSAY %~ UNIV-PARIS-SACLAY %~ CEA-UPSAY-SACLAY %~ IRAMIS %~ GS-PHYSIQUE %~ INSTITUT-SCIENCES-LUMIERE