Transition from spin ice to spin liquid——evolvement of structure and magnetic properties

Abstract

The polycrystal samples of Ho2-xTbxTi2O7（x=0，05，1，15，2） were prepared by solid reaction method. The result of X-ray diffraction （XRD） and dc susceptibility measurement from 2 K to 300 K both indicate that as the content of Tb3+，i.e. x，increases，the system crosses over from Ho2Ti2O7spin ice to Tb2Ti2O7 spin liquid，the lattice constant of cubic pyrochlore increases，while the Curie constant and effective magnetic moment decrease. Especially，the Curie-Weiss temperature decreases from positive to negative with the decrease of x，implying the transition from ferromagnetic Ho2Ti2O7 to anti-ferromagnetic Tb2Ti2O7. The detailed analysis shows that as x in Ho2-xTbxTi2O7 increases，the intensity of long-range dipolar interaction Dnn decreases. Being ferromagnetic or anti-ferromagnetic，and the change in intensity of long-range dipolar interaction, may be the two crucial factors influencing on the system to form spin ice state or cooperative paramagnetic state，i.e. the spin liquid state.