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Pressure effects on the dimerization in the spin-Peierls state of CuGe O 3

1995; American Physical Society; Volume: 52; Issue: 21 Linguagem: Inglês

10.1103/physrevb.52.15364

1095-3795

Susumu Katano, Osamu Fujita, Jun Akimitsu, Masakazu Nishi,

Theoretical and Computational Physics

The dimerization in the spin-Peierls state of CuGe${\mathrm{O}}_{3}$ has been studied by neutron diffraction under high pressures up to 1.65 GPa. Effects of pressure on the chain direction along the $c$ axis are fairly small; however, the dimerization of Cu along this direction tends to decrease. In comparison with this small change, the effects on the oxygen displacements in the $\mathrm{ab}$ plane are rather large. The shift of oxygen atoms decreases also along the $a$ axis; on the other hand, the shift along the $b$ axis increases. These characteristic changes in the dimerization together with those in the bond lengths and bond angles are briefly discussed in connection with the large enhancement of the transition temperature ${T}_{\mathrm{sp}}$ and also with the decrease in the exchange energy $J$ which were recently observed under high pressure.