We have measured the temperature dependences of the thermal conductivity of LaSrFe1−xGaxO4 (x ¼ 0; 0:01) single crystals with a two-dimensional (2D) antiferromagnetic (AF) spin network of Fe3+ spins with the spin quantum number S = 5=2 in zero field and a magnetic field of 14 T. A peak originating from the thermal conductivity due to spins, κspin, has been observed at ∼110 K in the temperature dependence of the thermal conductivity in the ab-plane parallel to the 2D AF spin network. The maximum value of κspin is ∼12 W=Km, which is comparable to that in La2CuO4 with a 2D AF spin system of S = 1=2. By comparison with the temperature dependence of κspin in La2CuO4, we have found that the peak temperature where κspin shows a peak tends to increase with increasing width of the magnetic energy band, namely, with increasing product of the superexchange interaction between the nearest neighbor spins and the spin quantum number, JS, in 2D AF spin systems. Moreover, it has been concluded that κspin is expected to be enhanced by reducing the amount of impurities and imperfections in a crystal with a 2D AF spin network with a large JS value.
ASJC Scopus subject areas
- Physics and Astronomy(all)