Magnetic Characterization and Low-Temperature Heat Transport Properties of the Orthoferrites RFeO3 ( $R =$ Rare Earth) Single Crystals

We have studied the magnetic characterization and low-temperature heat transport properties of the orthoferrites RFeO
₃
(R = Gd, Dy, Ho, and Y) single crystals. At 40-60 K, the M-T curves with H = 0.1 T (// c) in HoFeO
₃
and DyFeO
₃
show distinct step-like transitions, which are caused by the spin-reorientation transition of Fe
³⁺
. The magnetization and specific heat indicate that GdFeO
₃
and DyFeO
₃
have the antiferromagnetic order of R
³⁺
at 2.2 and 4.1 K, respectively, while HoFeO
₃
does not exhibit the antiferromagnetic order of R
³⁺
at temperatures down to 2 K. Applying the magnetic field along the c-axis, the magnetic structures of R
³⁺
or Fe
³⁺
can be changed for DyFeO
₃
and GdFeO
₃
. The thermal conductivities (k) of these materials display obvious differences. In particular, the k(T) curve of HoFeO
₃
shows a broad concave at 40-140 K, which is caused by the resonant phonon scattering by Ho
³⁺
. These results point to the clear difference in the interaction between R
³⁺
and Fe
³⁺
ions among these materials.