f-electron dependence of the physical properties of REAIB_4; an AIB_2-type analogous 'tiling' compound

摘要

á-HoAlB_4 and á-ErAlB_4 were synthesized, and their magnetic properties and specific heat investigated in comparison with other known rare-earth analogs. Recent developments in rare-earth aluminoboride compounds with two-dimensional boron layers have attracted interest due to the heavy fermion superconductivity in ?-YbAlB_4, multiple anomalies manifesting below the Neel temperatures in á-TmAlB_4 attributed to intrinsic building defects, and field stable state in Tm^ATBg. Strikingly, á-HoAlB_4 and á-ErAlB_4 were discovered to exhibit superparamagnetic or spin glass behavior in contrast to the magnetic ordering or nonordering observed for the other rare-earth element compounds.