Effect of Short-Range Ferromagnetic Ordering on the Electrical Transport Properties of (La_(0.9)Bi_(0.1))_(2/3)Ca_(1/3)MnO_3 in the Magnetic Field up to 40 T

摘要

The temperature and magnetic field dependence of the resistance of polycrystalline sample (La_(0.9)Bi_(0.1))_(2/3)Ca_(1/3)MnO_3 was investigated in pulsed high magnetic field up to 40 T over a wide temperature region. In order to describe the magnetotransport properties of the sample, an extended Mott hopping conduction model was employed. Instead of B_J(gμ_BJ(T)B/k_BT) in the ferromagnetic (FM) state and B_J~2(gμ_BJ(T)B/k_BT) in the paramagnetic (PM) state, the magnetic field dependence of the resistance could scale nicely with the Brillouin function B_J(gμ_BJ(T)B/k_BT) in all the given temperatures (above and below the Curie temperature T_c). The deduced value of the average spin moment J(T) increases with the increasing of the temperature and reaches the maximum value (～35) around T_c. The large value of J(T) indicate the presence of magnetic clusters in the sample which is induced by the short-range ferromagnetic ordering, however, compared to the un-doped compound La_(2/3)Ca_(1/3)MnO_3, the value of J(T) is much smaller, which might be ascribe to the location of the 6s~2 lone pair electrons of Bi~(3+) ions in the sample (La_(0.9)Bi_(0.1))_(2/3)Ca_(1/3)MnO_3.