Magnetic and dielectric study of RSrMnO (R = Gd, Tb and Dy)

Yoshii, Kenji  ; Hiramitsu, Yusuke*; Okajima, Yuka*; Yoneda, Yasuhiro   ; Nishihata, Yasuo; Mizuki, Junichiro; Nakamura, Akio; Shimojo, Yutaka; Ishii, Yoshinobu*; Morii, Yukio; Ikeda, Naoshi*

Magnetic and dielectric properties of perovskite manganites RSrMnO (R = Gd, Tb and Dy) have been investigated. DC and AC magnetic measurements showed short-range glassy magnetic ordering at Tg about 40 K. Such ordering was observed by neutron diffraction and is ascribable to the size mismatch of R and Sr settled randomly at the same crystallographic site. Dielectric constants for each material were about 1000-10000 between about 50 K and 300 K and showed broad maximums above Tg. Dielectric dispersion showed poor coherency of the motion of polar regions, plausibly because of the size-mismatch effect; both the magnetic and dielectric properties of this system are governed by the randomness at the R/Sr site. The tan and EXAFS data suggest that the dielectric response is rooted in a transfer of the Mn-3d electrons.