Magnetic properties of nanocomposite and bulk rare earth titanates Ho2Ti2O7 and Yb2Ti2O7

Abstract Comparison of magnetic properties of nanocomposite and bulk samples of frustrated magnets is carried out. Classical spin ice material Ho2Ti2O7 and probable candidate of quantum spin ice material Yb2Ti2O7 are chosen as the objects of investigation. The nanocomposite samples contain titanate particles with the dimensions less than 50 nm into the interspherical voids of opal matrices. The magnetization curves and temperature dependences of magnetic susceptibility are measured. It has been established that the magnetic properties of bulk and nanocomposite rare earth titanates substantially differ. In the field of 30 kOe the magnetization value in bulk and nanocomposite titanate Ho2Ti2O7 differs not in proportion to the volume fraction of titanate in nanocomposite but several times more. For the bulk titanates Ho2Ti2O7 and Yb2Ti2O7 the Curie-Weiss law approximately holds in the temperature range from 2 to 50 K but the deviations are essential in wider temperature range. Whereas for nanocomposite titanates there is a difference between the temperature dependences of susceptibility measured in the low field of 100 Oe under cooling and heating.