X-ray magnetic circular dichroism study of ${\mathrm{TbNi}}_2{\mathrm{B}}_2\mathrm{C}$

X-ray magnetic circular dichroism measurements were performed on ${\mathrm{TbNi}}_2{\mathrm{B}}_2\mathrm{C}$ in order to confirm the weak ferromagnetism reported for this material at low temperatures. Below approximately 8 K, an increase in the dichroic signal was observed at the Tb $L_{\mathrm{III}}$ edge, consistent with the onset of weak ferromagnetism involving the Tb ions. At an external magnetic field of 500 G, the ferromagnetic order parameter was obtained, and is in good agreement with the bulk magnetization data measured by a SQUID magnetometer.