Magnetic properties in Ca-dopesd Eu hexaboride

Abstract

Temperature- and field-dependent magnetization M(T,H) measurements were carried out for the series of Eu1-xCaxB6 compounds (x = 0.0, 0.13, 0.35, 0.54, 0.74, and 0.87). The small Ca doping in Eu1-xCaxB6 induced a suppression of a ferromagnetic transition temperature from Tc ≈ 12 K for EuB6 to Tc ≈ 5.5 K for Eu0.87Ca0.13B6. Interestingly, antiferromagnetic transition, rather than ferromagnetic transition, was observed in M(T) with H = 100 Oe at TN ≈ 4.5 K for Eu0.65Ca0.35B6 and at TN ≈ 3 K for Eu0.46Ca0.54B6. Temperature-dependent resistivity and specific heat data at low temperatures were presented and discussed in terms of the antiferromagnetic transition. With further increase of Ca doping, paramagnetic state was observed down to T = 2 K.