139La NQR Study of the Magnetic Properties of La2-xMxCuO4 (M=Ba, Sr) for 0 ≤x ≤0.08
Abstract
The magnetic properties of La2-xMxCuO4 (M=Ba, Sr) for 0 ≤x ≤0.08 have been investigated from 1.5 K to 300 K by the nuclear quadrupole resonance (NQR) of 139La (I=7/2). The electrical quadrupole relaxation process of 139La in La2CuO4 is dominant above 50 K in spite of the existence of the internal field at the La site due to the antiferromagnetic ordering of Cu-moments. At low temperature, the magnetic relaxation process becomes dominant. From the divergence of the nuclear relaxation rate, T1-1, of 139La, we obtain the magnetic phase diagram which consists of two distinct magnetic phases for 0 < x < 0.05. The internal field at the La-site changes discontinuously at T C* at which the temperature dependence of T1-1 shows a peak. This change can be interpreted by decrease of the transferred hyperfine fields from Cu spins through the apical oxygen of the CuO6 octahedron below T C*.
- Publication:
-
Journal of the Physical Society of Japan
- Pub Date:
- April 1994
- DOI:
- 10.1143/JPSJ.63.1560
- Bibcode:
- 1994JPSJ...63.1560W