Ferromagnetic order in Yb(Rh$_{0.73}$Co$_{0.27}$)$_{2}$Si$_{2}$
  We present the discovery of ferromagnetism in single crystalline Yb(Rh$_{0.73}$Co$_{0.27}$)$_{2}$Si$_{2}$ below $T_{C} = 1.30\,$K with a spontaneous magnetic moment of $0.1\,\mu_{B}$/Yb along the crystallographic c-axis. This is shown by the huge c-susceptibility peak, the hysteresis in magnetization as well as by the field-dependent susceptibility and specific heat data. This discovery motivates the reinvestigation of the magnetic order in Yb(Rh$_{1-x}$Co$_{x}$)$_{2}$Si$_{2}$ with $x < 0.27$ and in pure YbRh$_{2}$Si$_{2}$ under small pressures with field along the $c$-direction to look for low-lying ferromagnetic order. 
S. Lausberg, A. Hannaske, A. Steppke, L. Steinke, T. Gruner, C.   Krellner, C. Klingner, M. Brando, C. Geibel and F. Steglich
cond-mat.str-el