Magnetic and electronic irreversibility and relaxation in Eu(1-x)La(x)B(6) (x=0.15 and 0.18)

Abstract

We have investigated the magnetic and electronic transport properties of Eu(1-x)La(x)B(6) (x=0.15 and 0.18). Temperature-dependent magnetization of Eu(1-x)La(x)B(6) (x=0.15 and 0.18) exhibited antiferromagneticlike ground state with transition temperature T(m)approximate to 5 K and thermal hysteresis below T(m) between field-cooled and zero-field-cooled modes with the magnetic field of H=0.1 kOe. Time dependent isothermal remnant magnetization M(IRM) of Eu(1-x)La(x)B(6) (x=0.15 and 0.18) was found to follow logarithmic magnetic relaxation behavior M(t)=M(0)-M(1) log(t). The temperature-dependent resistivity rho(T) shows anomalous increase at low temperatures below T <= 20 K, suppressed by magnetic field, which can be explained by magnetic polaron picture. Interestingly, field dependent electrical resistivity rho(H) for Eu(1-x)La(x)B(6) (x=0.15 and 0.18) showed irreversibility between increasing and decreasing field. The relaxation of rho(H -> 0) was found to follow the general stretched exponential form, rho(t)=A+B exp(-t/tau)(gamma). (c) 2008 American Institute of Physics.