Study of the specific heat of a CeCoAl 4 single crystal in high magnetic fields

Abstract

The specific heat of a CeCoAl 4 single crystal has been studied in magnetic fields up to 17.5 T. In zero field, this compound has been found to order antiferromagnetically below the Néel temperature of about 13.5 K. The effect of the magnetic field is different when it is applied along the different crystallographic axes. Along the a-axis, with increasing magnetic field, the Néel temperature slightly decreases and reaches a value of 12.7 K at 17.5 T. Along the b-axis, the Néel temperature decreases more strongly with increasing magnetic field. At 16 T, we found a value of T N of about 6.9 K. At 17.5 T, along the b-axis, we observed a rather broad peak in the specific heat which is associated with a transition from paramagnetism to ferromagnetic order. Along the c-axis, a drastic change in the specific heat occurs at a field between 7–8 T. At 7 T, the value of T N is about 9 K. At fields higher than 8 T, the specific heat is evidently characterised by a transition from paramagnetism to ferromagnetic order. The critical values of the magnetic field above which ferromagnetic order is formed at low temperature turn out to be consistent with the measurements of the magnetisation curves at 4.2 K.