Magnetic transitions in YbCoSi

YbCoSiにおける磁気転移

金子 耕士   ; Stockert, O.*; Mufti, N.*; Kiefer, K.*; Klingner, C.*; Krellner, C.*; Geibel, C.*; Steglich, F.*

Kaneko, Koji; Stockert, O.*; Mufti, N.*; Kiefer, K.*; Klingner, C.*; Krellner, C.*; Geibel, C.*; Steglich, F.*

YbCoSi with the tetragonal ThCrSi-type structure is an isoelectronic compound to YbRhSi. At zero magnetic field YbCoSi undergoes two magnetic transitions at =0.9,K and =1.7,K,and exhibits a complex magnetic phase diagram for small applied fields, lower than =2,T. Therefore, YbCoSi is not only a good reference to YbRhSi but also an interesting system in its own to study its magnetic properties. In order to reveal the magnetic structure of YbCoSi, a neutron powder diffraction experiment was carried out. At zero field, several superlattice reflections were clearly observed at 0.5,K. By heating up to 1.1,K, to the intermediate phase, a substantial change in both, the peak position and the intensity ratio of the magnetic reflection was found. We will propose a possible magnetic structure for both phases.