We report the results of Raman scattering measurements which determine the pressure dependence of the in-plane exchange coupling constant J in magnetic La2CuO4 for pressure between 1bar and 100 kbar. We find that pressure increases the Neel temperature TN much more rapidly than J. This result together with the theory for a quasi two-dimensional magnetic system then suggests that the interplanar exchange coupling decreases with pressure. © 1991.

We have measured the two magnon Raman scattering spectrum of magnetic La2CuO4 at pressures of up to 100 kbar. Analysis of the moments of the two magnon line shape indicates that the renormalization parameters resulting from spin fluctuations are essentially pressure independent in this pressure range. Our results provide the first direct determination of the pressure dependence of the in plane exchange coupling constant J. The pressure dependence of J is compared with that of the Néel temperature and discussed in the context of recent theories for quasi two dimensional magnetic systems. © 1991, American Institute of Physics. All rights reserved.

Using high-pressure Raman scattering, we have directly measured the pressure dependence of the in-plane superexchange interaction J in antiferromagnetic La2CuO4 between 1 bar and 100 kbar. We find that J has a substantially weaker pressure dependence than in conventional magnets. We also show that the Hubbard-model parameters describing the low-energy electronic structure are significantly influenced by out-of-plane compositional and structural variations. Finally, we show that the relationship between J and the Neél temperature TN is poorly described by current theory. © 1991 The American Physical Society.