Low-temperature structural and magnetic phase transitions in multiferroic GdFe3(BO3)4

Abstract X-ray analysis revealed that at temperature decreasing from room temperature to T str = 155 K the crystal unit cell GdFe 3 (BO 3 ) 4 is reduced only along the c axis (at 0.01 A), while the a and b axes are unchanged within the error limits. The volume of the crystal decreases uniformly in the direction of all three axes at 155–80 K. At 80–30 K the crystal volume is decreased only by reduction of the parameters a and b , while the parameter c increases conversely. In the paramagnetic region Mossbauer spectra do not distinguish between the two structural positions of iron ions Fe1 and Fe2, appearing at T T str . Below the temperature of the magnetic phase transition at T N = 38.0(1) K the Mossbauer data indicate quasi-one-dimensional magnetic ordering of iron moments in the sublattice Fe2 and a two-dimensional one in the iron sublattice Fe1. The dynamics of spin reorientation in sublattices Fe1 and Fe2 is studied in detail.